Prevent integer underflow when truncating vlist string#4
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jaredmauch wants to merge 1 commit intofutatuki:mainfrom
Closed
Prevent integer underflow when truncating vlist string#4jaredmauch wants to merge 1 commit intofutatuki:mainfrom
jaredmauch wants to merge 1 commit intofutatuki:mainfrom
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The code accesses vlist[vlistlen - 1] without checking if vlistlen > 0. If vlistlen is 0 (due to decrements in the switch statement), then vlistlen - 1 would underflow to SIZE_MAX (since vlistlen is size_t), causing a massive buffer overflow. Fix by checking that vlistlen > 0 and that vlistlen is within the actual string bounds before accessing vlist[vlistlen - 1]. This prevents both integer underflow and buffer overflow vulnerabilities. This complements the upstream fix for the buffer overflow issue by adding explicit bounds checking.
futatuki
reviewed
Dec 23, 2025
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| vlist[vlistlen - 1] = '\0'; | ||
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Owner
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vlistlen here always >= 1 because p should be NULL terminated string and *p points other than \0 (} is not found while scanning). And then vlist is never never truncated as I wrote the comment on PR #3, I think.
Owner
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My conclusion is that this check is redundant and is not needed if |
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The code accesses vlist[vlistlen - 1] without checking if vlistlen > 0. If vlistlen is 0 (due to decrements in the switch statement), then vlistlen - 1 would underflow to SIZE_MAX (since vlistlen is size_t), causing a buffer overflow.
Fix by checking that vlistlen > 0 and that vlistlen is within the actual string bounds before accessing vlist[vlistlen - 1]. This prevents both integer underflow and buffer overflow vulnerabilities.