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| author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2016-12-15 18:27:10 +0000 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2016-12-16 11:30:20 -0200 |
| commit | b224637928e9fc04e3cef3e10d02ccf042d01584 (patch) | |
| tree | 5039ee55ad35414936bff34c31c5b3bd05a31e3a /sysdeps/powerpc/powerpc64/power7 | |
| parent | e4d6a83565479c533aabae9046377a59712a5b22 (diff) | |
| download | glibc-b224637928e9fc04e3cef3e10d02ccf042d01584.tar.gz | |
Fix powerpc64/power7 memchr for large input sizes
Current optimized powercp64/power7 memchr uses a strategy to check for
p versus align(p+n) (where 'p' is the input char pointer and n the
maximum size to check for the byte) without taking care for possible
overflow on the pointer addition in case of large 'n'.
It was triggered by 3038145ca23 where default rawmemchr (used to
created ppc64 rawmemchr in ifunc selection) now uses memchr (p, c, (size_t)-1)
on its implementation.
This patch fixes it by implement a satured addition where overflows
sets the maximum pointer size to UINTPTR_MAX.
Checked on powerpc64le-linux-gnu.
[BZ# 20971]
* sysdeps/powerpc/powerpc64/power7/memchr.S (__memchr): Avoid
overflow in pointer addition.
* string/test-memchr.c (do_test): Add an argument to pass as
the size on memchr.
(test_main): Add check for SIZE_MAX.
Diffstat (limited to 'sysdeps/powerpc/powerpc64/power7')
| -rw-r--r-- | sysdeps/powerpc/powerpc64/power7/memchr.S | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/sysdeps/powerpc/powerpc64/power7/memchr.S b/sysdeps/powerpc/powerpc64/power7/memchr.S index 03f0d7c2dd..0737100fd5 100644 --- a/sysdeps/powerpc/powerpc64/power7/memchr.S +++ b/sysdeps/powerpc/powerpc64/power7/memchr.S @@ -26,7 +26,17 @@ ENTRY (__memchr) dcbt 0,r3 clrrdi r8,r3,3 insrdi r4,r4,8,48 - add r7,r3,r5 /* Calculate the last acceptable address. */ + + /* Calculate the last acceptable address and check for possible + addition overflow by using satured math: + r7 = r3 + r5 + r7 |= -(r7 < x) */ + add r7,r3,r5 + subfc r6,r3,r7 + subfe r9,r9,r9 + extsw r6,r9 + or r7,r7,r6 + insrdi r4,r4,16,32 cmpldi r5,32 li r9, -1 |