Fix off-by-one heap-buffer-overflow in get_or_create_temp_file()#493
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xroche wants to merge 1 commit intoDataDog:mainfrom
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Fix off-by-one heap-buffer-overflow in get_or_create_temp_file()#493xroche wants to merge 1 commit intoDataDog:mainfrom
xroche wants to merge 1 commit intoDataDog:mainfrom
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The malloc size calculation in get_or_create_temp_file() allocates
strlen(tmp_dir) + strlen(prefix) + strlen(data.digest) + 2 bytes,
but the constructed path "tmp_dir/prefix-digest\0" requires +3 bytes
(for '/', '-', and the NUL terminator), not +2.
This causes a 1-byte heap-buffer-overflow when strcat writes the NUL
terminator of data.digest past the end of the allocated buffer.
Make the arithmetic explicit by writing each component's length
separately (+1 for each separator and the terminator), matching the
four strcat calls that follow.
The sister function create_temp_file() is not affected: its format
"tmp_dir/prefix.XXXXXX" only has one separator ('/'), and ".XXXXXX"
is already measured by strlen(".XXXXXX").
Fixes DataDog#492
Collaborator
|
Thank you! We will look at why we did not pick this up on asan builds. |
Author
@r1viollet We detected several other issues; what would be the most efficient way to address them ?
Thanks! |
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What does this PR do?
Fix off-by-one heap-buffer-overflow in
get_or_create_temp_file()insrc/lib/loader.c.The
mallocallocatesstrlen(tmp_dir) + strlen(prefix) + strlen(data.digest) + 2, but the pathtmp_dir/prefix-digest\0needs+3(for/,-, and\0). The NUL terminator overflows by 1 byte.Motivation
Detected via AddressSanitizer when
dlopeninglibdd_profiling.so(v0.23.0 release):The sister function
create_temp_file()is correct (only 1 separator).Additional Notes
In practice, the 1-byte NUL overflow is benign on most allocators — it only crashes under ASAN.
How to test the change?
dlopenlibdd_profiling.sounder AddressSanitizer.Classification
Fixes #492