fuzz: fix stack-use-after-scope in LLVMFuzzerTestOneInput#881
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oliverchang wants to merge 1 commit intoPCRE2Project:mainfrom
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fuzz: fix stack-use-after-scope in LLVMFuzzerTestOneInput#881oliverchang wants to merge 1 commit intoPCRE2Project:mainfrom
oliverchang wants to merge 1 commit intoPCRE2Project:mainfrom
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A variable `callout_count` is declared within the scope of a `for` loop in the function `LLVMFuzzerTestOneInput`. The address of this variable is passed to the function `pcre2_set_callout()` and stored within the variable `match_context`. The variable `match_context` is defined outside the loop, initialized during the first loop iteration, and persists for the second iteration. The address of `callout_count` is a stale stack location in the second iteration. When `pcre2_match()` is called in the second iteration, a callback attempts to access this address, resulting in a stack-use-after-scope error. This patch moves the declaration of `callout_count` to the function scope, ensuring its lifetime covers the entire duration that `match_context` is active. Co-authored-by: CodeMender <codemender-patching@google.com> Fixes: https://issues.oss-fuzz.com/issues/478301105
Contributor
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Please note that this should be considered an AI contribution. |
Contributor
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@oliverchang, as requested in #882, can you please provide more context for this PR? Is there something in OSS-Fuzz we are not seeing, or was this a spurious patch? |
Author
This is a spurious patch caused by a bad bug in our infrastructure. Please ignore this one, and sorry again for the noise! |
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A variable
callout_countis declared within the scope of aforloop in the functionLLVMFuzzerTestOneInput. The address of this variable is passed to the functionpcre2_set_callout()and stored within the variablematch_context.The variable
match_contextis defined outside the loop, initialized during the first loop iteration, and persists for the second iteration. The address ofcallout_countis a stale stack location in the second iteration. Whenpcre2_match()is called in the second iteration, a callback attempts to access this address, resulting in a stack-use-after-scope error.This patch moves the declaration of
callout_countto the function scope, ensuring its lifetime covers the entire duration thatmatch_contextis active.Fixes: https://issues.oss-fuzz.com/issues/478301105