Fix runtime_events by Rokcas · Pull Request #1 · edwintorok/ocaml

Rokcas · 2023-02-24T21:41:26Z

No description provided.

The module level one is not rendered, and confuses lintapidiff. Signed-off-by: Edwin Török <edwin@etorok.net>

They are not valid OCaml syntax, and the processed file is committed into Git already.

Signed-off-by: Edwin Török <edwin@etorok.net>

@SInCE

TODO: the @SInCE on this was different between labeled and unlabeled so this will be more complicated to handle in lintapidiff. Signed-off-by: Edwin Török <edwin@etorok.net>

Signed-off-by: Edwin Török <edwin@etorok.net>

edwintorok · 2023-02-27T00:20:16Z

I've rebase and manually merged these into my branch, see the top 2 commits here, thanks!
https://github.com/edwintorok/ocaml/commits/lintapidiff

Reported by `-fsanitize=memory`: ``` > ==102752==WARNING: MemorySanitizer: use-of-uninitialized-value > #0 0x7f2ba7fb4ea4 in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:496:18 > #1 0x7f2ba7fbc016 in caml_ml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:1207:9 > ocaml#2 0x59ba5c in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 > ocaml#3 0x5a9220 in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 > ocaml#4 0x540d6b in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 > ocaml#5 0x7f2ba8120087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#6 0x7f2ba812014a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 617637580ee48eff08a2bce790e1667ad09f3b69) > > Uninitialized value was stored to memory at > #0 0x7f2ba7fb4e9d in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:497:69 > #1 0x7f2ba7fbc016 in caml_ml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:1207:9 > ocaml#2 0x59ba5c in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 > ocaml#3 0x5a9220 in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 > ocaml#4 0x540d6b in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 > ocaml#5 0x7f2ba8120087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#6 0x7f2ba812014a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 617637580ee48eff08a2bce790e1667ad09f3b69) > > Uninitialized value was created by an allocation of 'buf' in the stack frame > #0 0x7f2ba7fb3dbc in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:402:7 > ``` This is in fact an EV_LIFECYCLE with EV_RING_STOP, which has 0 additional data, and thus msg_length 2: ``` runtime/runtime_events.c: EV_RUNTIME, (ev_message_type){.runtime=EV_LIFECYCLE}, EV_RING_STOP, 0, ``` Attempting to read from `buf[2]` would read uninitialized data (or potentially beyond the end of the buffer). Check `msg_length` before reading. Signed-off-by: Edwin Török <edwin.torok@cloud.com>

Bigarrays are printed in the toplevel as `<abstr>`, but ObjTbl.mem computes a hash. However bigarrays are uninitialized when allocated, so this seems to be a genuine bug: ``` ==133712==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x4e6d11 in caml_ba_hash /var/home/edwin/git/ocaml/runtime/bigarray.c:486:45 #1 0x52474a in caml_hash /var/home/edwin/git/ocaml/runtime/hash.c:251:35 ocaml#2 0x599ebf in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1065:14 ocaml#3 0x5a909a in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 ocaml#4 0x540ccb in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 ocaml#5 0x7f0910abb087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#6 0x7f0910abb14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) Uninitialized value was created by a heap allocation #0 0x47d306 in malloc (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x47d306) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) #1 0x4e7960 in caml_ba_alloc /var/home/edwin/git/ocaml/runtime/bigarray.c:246:12 ocaml#2 0x4e801f in caml_ba_create /var/home/edwin/git/ocaml/runtime/bigarray.c:673:10 ocaml#3 0x59b8fc in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 ocaml#4 0x5a909a in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 ocaml#5 0x540ccb in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 ocaml#6 0x7f0910abb087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#7 0x7f0910abb14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#8 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) SUMMARY: MemorySanitizer: use-of-uninitialized-value /var/home/edwin/git/ocaml/runtime/bigarray.c:486:45 in caml_ba_hash ``` Suppress it for now until a solution is found. The testsuite passes now: ``` Summary: 1334 tests passed 103 tests skipped 0 tests failed 0 tests not started (parent test skipped or failed) 0 unexpected errors 1437 tests considered ``` Signed-off-by: Edwin Török <edwin.torok@cloud.com>

Reported by `-fsanitize=memory`: ``` > ==102752==WARNING: MemorySanitizer: use-of-uninitialized-value > #0 0x7f2ba7fb4ea4 in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:496:18 > #1 0x7f2ba7fbc016 in caml_ml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:1207:9 > ocaml#2 0x59ba5c in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 > ocaml#3 0x5a9220 in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 > ocaml#4 0x540d6b in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 > ocaml#5 0x7f2ba8120087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#6 0x7f2ba812014a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 617637580ee48eff08a2bce790e1667ad09f3b69) > > Uninitialized value was stored to memory at > #0 0x7f2ba7fb4e9d in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:497:69 > #1 0x7f2ba7fbc016 in caml_ml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:1207:9 > ocaml#2 0x59ba5c in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 > ocaml#3 0x5a9220 in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 > ocaml#4 0x540d6b in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 > ocaml#5 0x7f2ba8120087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#6 0x7f2ba812014a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 617637580ee48eff08a2bce790e1667ad09f3b69) > > Uninitialized value was created by an allocation of 'buf' in the stack frame > #0 0x7f2ba7fb3dbc in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:402:7 > ``` This is in fact an EV_LIFECYCLE with EV_RING_STOP, which has 0 additional data, and thus msg_length 2: ``` runtime/runtime_events.c: EV_RUNTIME, (ev_message_type){.runtime=EV_LIFECYCLE}, EV_RING_STOP, 0, ``` Attempting to read from `buf[2]` would read uninitialized data (or potentially beyond the end of the buffer). Check `msg_length` before reading. Signed-off-by: Edwin Török <edwin.torok@cloud.com>

Bigarrays are printed in the toplevel as `<abstr>`, but ObjTbl.mem computes a hash. However bigarrays are uninitialized when allocated, so this seems to be a genuine bug: ``` ==133712==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x4e6d11 in caml_ba_hash /var/home/edwin/git/ocaml/runtime/bigarray.c:486:45 #1 0x52474a in caml_hash /var/home/edwin/git/ocaml/runtime/hash.c:251:35 ocaml#2 0x599ebf in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1065:14 ocaml#3 0x5a909a in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 ocaml#4 0x540ccb in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 ocaml#5 0x7f0910abb087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#6 0x7f0910abb14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) Uninitialized value was created by a heap allocation #0 0x47d306 in malloc (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x47d306) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) #1 0x4e7960 in caml_ba_alloc /var/home/edwin/git/ocaml/runtime/bigarray.c:246:12 ocaml#2 0x4e801f in caml_ba_create /var/home/edwin/git/ocaml/runtime/bigarray.c:673:10 ocaml#3 0x59b8fc in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 ocaml#4 0x5a909a in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 ocaml#5 0x540ccb in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 ocaml#6 0x7f0910abb087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#7 0x7f0910abb14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#8 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) SUMMARY: MemorySanitizer: use-of-uninitialized-value /var/home/edwin/git/ocaml/runtime/bigarray.c:486:45 in caml_ba_hash ``` The hashing is only needed to avoid recursion, skip it when the OCaml value doesn't contain further nested OCaml values, i.e. when it wouldn't be scanned by the GC. The testsuite passes now: ``` Summary: 1335 tests passed 102 tests skipped 0 tests failed 0 tests not started (parent test skipped or failed) 0 unexpected errors 1437 tests considered ``` Suggested-by: Gabriel Scherer <gabriel.scherer@gmail.com> Signed-off-by: Edwin Török <edwin.torok@cloud.com>

Found by -fsanitize=memory -fsanitize-memory-track-origins: ``` > ==102752==WARNING: MemorySanitizer: use-of-uninitialized-value > #0 0x7f2ba7fb4ea4 in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:496:18 > #1 0x7f2ba7fbc016 in caml_ml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:1207:9 > ocaml#2 0x59ba5c in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 > ocaml#3 0x5a9220 in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 > ocaml#4 0x540d6b in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 > ocaml#5 0x7f2ba8120087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#6 0x7f2ba812014a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 617637580ee48eff08a2bce790e1667ad09f3b69) > > Uninitialized value was stored to memory at > #0 0x7f2ba7fb4e9d in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:497:69 > #1 0x7f2ba7fbc016 in caml_ml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:1207:9 > ocaml#2 0x59ba5c in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 > ocaml#3 0x5a9220 in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 > ocaml#4 0x540d6b in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 > ocaml#5 0x7f2ba8120087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#6 0x7f2ba812014a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 617637580ee48eff08a2bce790e1667ad09f3b69) > > Uninitialized value was created by an allocation of 'buf' in the stack frame > #0 0x7f2ba7fb3dbc in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:402:7 > ``` This is in fact an EV_LIFECYCLE with EV_RING_STOP, which has 0 additional data, and thus msg_length 2: ``` runtime/runtime_events.c: EV_RUNTIME, (ev_message_type){.runtime=EV_LIFECYCLE}, EV_RING_STOP, 0, ``` Attempting to read from `buf[2]` would read uninitialized data. Signed-off-by: Edwin Török <edwin.torok@cloud.com>

The toplevel printer detects cycles by keeping a hashtable of values that it has already traversed. However, some OCaml runtime types (at least bigarrays) may be partially uninitialized, and hashing them at arbitrary program points may read uninitialized memory. In particular, the OCaml testsuite fails when running with a memory-sanitizer enabled, as bigarray printing results in reads to uninitialized memory: ``` ==133712==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x4e6d11 in caml_ba_hash /var/home/edwin/git/ocaml/runtime/bigarray.c:486:45 #1 0x52474a in caml_hash /var/home/edwin/git/ocaml/runtime/hash.c:251:35 ocaml#2 0x599ebf in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1065:14 ocaml#3 0x5a909a in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 ocaml#4 0x540ccb in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 ocaml#5 0x7f0910abb087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#6 0x7f0910abb14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) Uninitialized value was created by a heap allocation #0 0x47d306 in malloc (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x47d306) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) #1 0x4e7960 in caml_ba_alloc /var/home/edwin/git/ocaml/runtime/bigarray.c:246:12 ocaml#2 0x4e801f in caml_ba_create /var/home/edwin/git/ocaml/runtime/bigarray.c:673:10 ocaml#3 0x59b8fc in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 ocaml#4 0x5a909a in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 ocaml#5 0x540ccb in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 ocaml#6 0x7f0910abb087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#7 0x7f0910abb14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#8 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) SUMMARY: MemorySanitizer: use-of-uninitialized-value /var/home/edwin/git/ocaml/runtime/bigarray.c:486:45 in caml_ba_hash ``` The only use of hashing in genprintval is to avoid cycles, that is, it is only useful for OCaml values that contain other OCaml values (including possibly themselves). Bigarrays cannot introduce cycles, and they are always printed as "<abstr>" anyway. The present commit proposes to be more conservative in which values are hashed by the cycle detector to avoid this issue: we skip hashing any value with tag above No_scan_tag -- which may not contain any OCaml values. Suggested-by: Gabriel Scherer <gabriel.scherer@gmail.com> Signed-off-by: Edwin Török <edwin.torok@cloud.com>

Found by -fsanitize=memory -fsanitize-memory-track-origins: ``` > ==102752==WARNING: MemorySanitizer: use-of-uninitialized-value > #0 0x7f2ba7fb4ea4 in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:496:18 > #1 0x7f2ba7fbc016 in caml_ml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:1207:9 > ocaml#2 0x59ba5c in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 > ocaml#3 0x5a9220 in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 > ocaml#4 0x540d6b in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 > ocaml#5 0x7f2ba8120087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#6 0x7f2ba812014a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 617637580ee48eff08a2bce790e1667ad09f3b69) > > Uninitialized value was stored to memory at > #0 0x7f2ba7fb4e9d in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:497:69 > #1 0x7f2ba7fbc016 in caml_ml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:1207:9 > ocaml#2 0x59ba5c in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 > ocaml#3 0x5a9220 in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 > ocaml#4 0x540d6b in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 > ocaml#5 0x7f2ba8120087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#6 0x7f2ba812014a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) > ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 617637580ee48eff08a2bce790e1667ad09f3b69) > > Uninitialized value was created by an allocation of 'buf' in the stack frame > #0 0x7f2ba7fb3dbc in caml_runtime_events_read_poll /var/home/edwin/git/ocaml/otherlibs/runtime_events/runtime_events_consumer.c:402:7 > ``` This is in fact an EV_LIFECYCLE with EV_RING_STOP, which has 0 additional data, and thus msg_length 2: ``` runtime/runtime_events.c: EV_RUNTIME, (ev_message_type){.runtime=EV_LIFECYCLE}, EV_RING_STOP, 0, ``` Attempting to read from `buf[2]` would read uninitialized data. Signed-off-by: Edwin Török <edwin.torok@cloud.com>

…l#13294) The toplevel printer detects cycles by keeping a hashtable of values that it has already traversed. However, some OCaml runtime types (at least bigarrays) may be partially uninitialized, and hashing them at arbitrary program points may read uninitialized memory. In particular, the OCaml testsuite fails when running with a memory-sanitizer enabled, as bigarray printing results in reads to uninitialized memory: ``` ==133712==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x4e6d11 in caml_ba_hash /var/home/edwin/git/ocaml/runtime/bigarray.c:486:45 #1 0x52474a in caml_hash /var/home/edwin/git/ocaml/runtime/hash.c:251:35 ocaml#2 0x599ebf in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1065:14 ocaml#3 0x5a909a in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 ocaml#4 0x540ccb in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 ocaml#5 0x7f0910abb087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#6 0x7f0910abb14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) Uninitialized value was created by a heap allocation #0 0x47d306 in malloc (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x47d306) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) #1 0x4e7960 in caml_ba_alloc /var/home/edwin/git/ocaml/runtime/bigarray.c:246:12 ocaml#2 0x4e801f in caml_ba_create /var/home/edwin/git/ocaml/runtime/bigarray.c:673:10 ocaml#3 0x59b8fc in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14 ocaml#4 0x5a909a in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9 ocaml#5 0x540ccb in main /var/home/edwin/git/ocaml/runtime/main.c:37:3 ocaml#6 0x7f0910abb087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#7 0x7f0910abb14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef) ocaml#8 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37) SUMMARY: MemorySanitizer: use-of-uninitialized-value /var/home/edwin/git/ocaml/runtime/bigarray.c:486:45 in caml_ba_hash ``` The only use of hashing in genprintval is to avoid cycles, that is, it is only useful for OCaml values that contain other OCaml values (including possibly themselves). Bigarrays cannot introduce cycles, and they are always printed as "<abstr>" anyway. The present commit proposes to be more conservative in which values are hashed by the cycle detector to avoid this issue: we skip hashing any value with tag above No_scan_tag -- which may not contain any OCaml values. Suggested-by: Gabriel Scherer <gabriel.scherer@gmail.com> Signed-off-by: Edwin Török <edwin.torok@cloud.com> Co-authored-by: Edwin Török <edwin.torok@cloud.com>

edwintorok and others added 7 commits February 24, 2023 19:24

uchar.mli: move @SInCE annotation to type

0f61eb7

The module level one is not rendered, and confuses lintapidiff. Signed-off-by: Edwin Török <edwin@etorok.net>

tools/lintapidiff: exclude .template.mli modules

9c9a512

They are not valid OCaml syntax, and the processed file is committed into Git already.

doc(Hashtbl): SeededHashedType.seeded_hash is 5.0+

010eda5

Signed-off-by: Edwin Török <edwin@etorok.net>

wip: floatarraylabeled

c4a5680

TODO: the @SInCE on this was different between labeled and unlabeled so this will be more complicated to handle in lintapidiff. Signed-off-by: Edwin Török <edwin@etorok.net>

Floatarraylabeled: fix documentation comment

7e58c61

Signed-off-by: Edwin Török <edwin@etorok.net>

Fix runtime_events

b56104d

Fix dynlink files

5522b62

edwintorok force-pushed the lintapidiff branch 3 times, most recently from 878e148 to b213dc7 Compare February 27, 2023 00:19

edwintorok closed this Feb 27, 2023

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Fix runtime_events#1

Fix runtime_events#1
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