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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2016-05-16 23:16:18 +0300 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2016-05-17 09:26:52 +0300 |
| commit | 4a6b27b79da5ccc6b85dc05bbe6a091e58be896a (patch) | |
| tree | 3b6c2e16d410844d288165218e62c037cb0e8ca3 /arch/x86/crypto | |
| parent | 256b1cfb9a346bb4808cd27b7b8f9b120f96491e (diff) | |
| download | linux-4a6b27b79da5ccc6b85dc05bbe6a091e58be896a.tar.xz | |
crypto: sha1-mb - make sha1_x8_avx2() conform to C function ABI
Megha Dey reported a kernel panic in crypto code. The problem is that
sha1_x8_avx2() clobbers registers r12-r15 without saving and restoring
them.
Before commit aec4d0e301f1 ("x86/asm/crypto: Simplify stack usage in
sha-mb functions"), those registers were saved and restored by the
callers of the function. I removed them with that commit because I
didn't realize sha1_x8_avx2() clobbered them.
Fix the potential undefined behavior associated with clobbering the
registers and make the behavior less surprising by changing the
registers to be callee saved/restored to conform with the C function
call ABI.
Also, rdx (aka RSP_SAVE) doesn't need to be saved: I verified that none
of the callers rely on it being saved, and it's not a callee-saved
register in the C ABI.
Fixes: aec4d0e301f1 ("x86/asm/crypto: Simplify stack usage in sha-mb functions")
Cc: stable@vger.kernel.org # 4.6
Reported-by: Megha Dey <megha.dey@linux.intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'arch/x86/crypto')
| -rw-r--r-- | arch/x86/crypto/sha-mb/sha1_x8_avx2.S | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/arch/x86/crypto/sha-mb/sha1_x8_avx2.S b/arch/x86/crypto/sha-mb/sha1_x8_avx2.S index 8e1b47792b31..c9dae1cd2919 100644 --- a/arch/x86/crypto/sha-mb/sha1_x8_avx2.S +++ b/arch/x86/crypto/sha-mb/sha1_x8_avx2.S @@ -296,7 +296,11 @@ W14 = TMP_ # ENTRY(sha1_x8_avx2) - push RSP_SAVE + # save callee-saved clobbered registers to comply with C function ABI + push %r12 + push %r13 + push %r14 + push %r15 #save rsp mov %rsp, RSP_SAVE @@ -446,7 +450,12 @@ lloop: ## Postamble mov RSP_SAVE, %rsp - pop RSP_SAVE + + # restore callee-saved clobbered registers + pop %r15 + pop %r14 + pop %r13 + pop %r12 ret ENDPROC(sha1_x8_avx2) |