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authorChris Wright <chrisw@sous-sol.org>2007-08-18 14:31:41 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-08-18 15:15:54 -0700
commitd34fda4a84c18402640a1a2342d6e6d9829e6db7 (patch)
treec6da4cdd6c63be258a32635e87b239c570d5f664
parent18115f45374d19ada218fc013aa5308baf5d283e (diff)
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x86: properly initialize temp insn buffer for paravirt patching
With commit ab144f5ec64c42218a555ec1dbde6b60cf2982d6 the patching code now collects the complete new instruction stream into a temp buffer before finally patching in the new insns. In some cases the paravirt patchers will choose to leave the patch site unpatched (length mismatch, clobbers mismatch, etc). This causes the new patching code to copy an uninitialized temp buffer, i.e. garbage, to the callsite. Simply make sure to always initialize the buffer with the original instruction stream. A better fix is to audit all the patchers and return proper length so that apply_paravirt() can skip copies when we leave the patch site untouched. Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/i386/kernel/alternative.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index 1b66d5c70ea..9f4ac8b02de 100644
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -366,6 +366,8 @@ void apply_paravirt(struct paravirt_patch_site *start,
unsigned int used;
BUG_ON(p->len > MAX_PATCH_LEN);
+ /* prep the buffer with the original instructions */
+ memcpy(insnbuf, p->instr, p->len);
used = paravirt_ops.patch(p->instrtype, p->clobbers, insnbuf,
(unsigned long)p->instr, p->len);