buffer: fix handling of empty string prepends.#6042
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htuch merged 1 commit intoenvoyproxy:masterfrom Feb 25, 2019
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Prepending an empty string seems to mess up libevent internally. evbuffer_prepend doesn't have a check for empty (unlike evbuffer_prepend_buffer which does). This then results in an allocation of an empty chain, which causes problems with a following move/append. This only seems to happen the the original buffer was created via addBufferFragment(), this forces the code execution path in evbuffer_prepend related to immutable buffers. Fixes oss-fuzz issue https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=13263. Risk level: Low Testing: Corpus entry and unit test added. Signed-off-by: Harvey Tuch <htuch@google.com>
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…oxy#6042. Signed-off-by: Harvey Tuch <htuch@google.com>
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Prepending an empty string seems to mess up libevent internally. evbuffer_prepend doesn't have a check for empty (unlike evbuffer_prepend_buffer which does). This then results in an allocation of an empty chain, which causes problems with a following move/append. This only seems to happen the the original buffer was created via addBufferFragment(), this forces the code execution path in evbuffer_prepend related to immutable buffers. Fixes oss-fuzz issue https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=13263. Risk level: Low Testing: Corpus entry and unit test added. Signed-off-by: Harvey Tuch <htuch@google.com> Signed-off-by: Fred Douglas <fredlas@google.com>
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Prepending an empty string seems to mess up libevent internally.
evbuffer_prepend doesn't have a check for empty (unlike evbuffer_prepend_buffer
which does). This then results in an allocation of an empty chain, which causes
problems with a following move/append. This only seems to happen the the
original buffer was created via addBufferFragment(), this forces the code
execution path in evbuffer_prepend related to immutable buffers.
Fixes oss-fuzz issue https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=13263.
Risk level: Low
Testing: Corpus entry and unit test added.
Signed-off-by: Harvey Tuch htuch@google.com