fs: fix out-of-bounds write in mkdtemp for long prefixes - #64770
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frandle331-yh wants to merge 1 commit into
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fs: fix out-of-bounds write in mkdtemp for long prefixes#64770frandle331-yh wants to merge 1 commit into
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## main #64770 +/- ##
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- Coverage 90.14% 90.13% -0.01%
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Files 744 744
Lines 242518 242519 +1
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- Misses 15396 15406 +10
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Renegade334
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Jul 27, 2026
Mkdtemp() allocated the template buffer as `length + strlen("XXXXXX")`,
leaving no room for the terminating NUL byte. For a single-byte prefix
long enough to force the heap allocation path (length + 6 > the
stack-buffer threshold), the terminating NUL was written one byte past
the end of the buffer -- a 1-byte heap-buffer-overflow flagged by
AddressSanitizer.
Allocate room for the terminating NUL, copy the suffix, and use
SetLengthAndZeroTerminate to set the correct length and write the
terminator, following the MaybeStackBuffer paradigm used elsewhere in
this file.
Signed-off-by: frandle331-yh <s1240100@gmail.com>
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Mkdtemp() allocated the template buffer as
length + strlen("XXXXXX"),leaving no room for the terminating NUL byte that snprintf() writes. For
a single-byte prefix long enough to force the heap allocation path
(length + 6 > the stack-buffer threshold), snprintf() wrote the six 'X'
characters plus its NUL one byte past the end of the buffer -- a 1-byte
heap-buffer-overflow flagged by AddressSanitizer.
Allocate one extra byte for the NUL terminator, matching the
+ 1already used by the sibling allocations in the same file.
Signed-off-by: frandle331-yh s1240100@gmail.com