This is a note to let you know that I've just added the patch titled crypto: sha1-mb - make sha1_x8_avx2() conform to C function ABI to the 4.6-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: crypto-sha1-mb-make-sha1_x8_avx2-conform-to-c-function-abi.patch and it can be found in the queue-4.6 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 4a6b27b79da5ccc6b85dc05bbe6a091e58be896a Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Date: Mon, 16 May 2016 15:16:18 -0500 Subject: crypto: sha1-mb - make sha1_x8_avx2() conform to C function ABI From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> commit 4a6b27b79da5ccc6b85dc05bbe6a091e58be896a upstream. 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") Reported-by: Megha Dey <megha.dey@xxxxxxxxxxxxxxx> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/crypto/sha-mb/sha1_x8_avx2.S | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) --- 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) Patches currently in stable-queue which might be from jpoimboe@xxxxxxxxxx are queue-4.6/crypto-sha1-mb-make-sha1_x8_avx2-conform-to-c-function-abi.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html