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Fix a bug in prof_dump_write

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The original logic can be disastrous if `PROF_DUMP_BUFSIZE` is less
than `slen` -- `prof_dump_buf_end + slen <= PROF_DUMP_BUFSIZE` would
always be `false`, so `memcpy` would always try to copy
`PROF_DUMP_BUFSIZE - prof_dump_buf_end` chars, which can be
dangerous: in the last round of the `while` loop it would not only
illegally read the memory beyond `s` (which might not always be
disastrous), but it would also illegally overwrite the memory beyond
`prof_dump_buf` (which can be pretty disastrous).  `slen` probably
has never gone beyond `PROF_DUMP_BUFSIZE` so we were just lucky.
This commit is contained in:
Yinan Zhang 2019-06-04 16:34:29 -07:00 committed by Qi Wang
parent d26636d566
commit e0a0c8d4bf
1 changed files with 1 additions and 1 deletions
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src/prof.c
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@ -1292,7 +1292,7 @@ prof_dump_write(bool propagate_err, const char *s) {
} }
} }
if (prof_dump_buf_end + slen <= PROF_DUMP_BUFSIZE) { if (prof_dump_buf_end + slen - i <= PROF_DUMP_BUFSIZE) {
/* Finish writing. */ /* Finish writing. */
n = slen - i; n = slen - i;
} else { } else {