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| author | Mark Wielaard <mark@klomp.org> | 2021-07-19 15:52:51 +0200 |
|---|---|---|
| committer | Mark Wielaard <mark@klomp.org> | 2021-07-19 15:52:51 +0200 |
| commit | 0aed4315b2f6c54f4efcf8a8d22e59a36e6eb30d (patch) | |
| tree | 774d0c3a232f303232a76783c7d12ef1aa1c9c87 | |
| parent | 779c57ea864d104bad88455535df9b26336349fd (diff) | |
| download | elfutils-0aed4315b2f6c54f4efcf8a8d22e59a36e6eb30d.tar.gz | |
libelf: Optimize elf_strptr.c validate_str by checking last char first
In most cases the last char of the sectio will be zero. Check that
first before calling memrchr. This is a minor optimization in normal
cases. But it helps asan a lot by removing the memrchr call in most
cases.
https://sourceware.org/bugzilla/show_bug.cgi?id=28101
Signed-off-by: Mark Wielaard <mark@klomp.org>
| -rw-r--r-- | libelf/ChangeLog | 5 | ||||
| -rw-r--r-- | libelf/elf_strptr.c | 4 |
2 files changed, 8 insertions, 1 deletions
diff --git a/libelf/ChangeLog b/libelf/ChangeLog index 62437c55..f521ed3d 100644 --- a/libelf/ChangeLog +++ b/libelf/ChangeLog @@ -1,3 +1,8 @@ +2021-07-19 Mark Wielaard <mark@klomp.org> + + * elf_strptr.c (validate_str): Check last char is zero first before + calling memrchr on the whole block. + 2021-06-09 Andrei Homescu <ah@immunant.com> * elf_getdata.c: Fix d_align for sections where alignment is larger diff --git a/libelf/elf_strptr.c b/libelf/elf_strptr.c index 76f2caf1..79a24d25 100644 --- a/libelf/elf_strptr.c +++ b/libelf/elf_strptr.c @@ -56,7 +56,9 @@ get_zdata (Elf_Scn *strscn) static bool validate_str (const char *str, size_t from, size_t to) { #if HAVE_DECL_MEMRCHR - return memrchr (&str[from], '\0', to - from) != NULL; + // Check end first, which is likely a zero terminator, to prevent function call + return ((to > 0 && str[to - 1] == '\0') + || (to - from > 0 && memrchr (&str[from], '\0', to - from - 1) != NULL)); #else do { if (to <= from) |