[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen stable-4.14] livepatch: account for patch offset when applying NOP patch
commit 57cd4b1c52881e49901b344ca3da00209c4689f7 Author: Jan Beulich <jbeulich@xxxxxxxx> AuthorDate: Mon Apr 4 15:58:04 2022 +0200 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Mon Apr 4 15:58:04 2022 +0200 livepatch: account for patch offset when applying NOP patch While not triggered by the trivial xen_nop in-tree patch on staging/master, that patch exposes a problem on the stable trees, where all functions have ENDBR inserted. When NOP-ing out a range, we need to account for this. Handle this right in livepatch_insn_len(). This requires livepatch_insn_len() to be called _after_ ->patch_offset was set. Fixes: 6974c75180f1 ("xen/x86: Livepatch: support patching CET-enhanced functions") Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> master commit: 8a87b9a0fb0564f9d68f0be0a0d1a17c34117b8b master date: 2022-03-31 10:45:46 +0200 --- xen/arch/x86/livepatch.c | 8 +++++--- xen/include/xen/livepatch.h | 2 +- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/xen/arch/x86/livepatch.c b/xen/arch/x86/livepatch.c index e94ac9b228..a3cb63a7ea 100644 --- a/xen/arch/x86/livepatch.c +++ b/xen/arch/x86/livepatch.c @@ -144,9 +144,6 @@ void noinline arch_livepatch_apply(struct livepatch_func *func) func->patch_offset = 0; old_ptr = func->old_addr; - len = livepatch_insn_len(func); - if ( !len ) - return; /* * CET hotpatching support: We may have functions starting with an ENDBR64 @@ -159,6 +156,11 @@ void noinline arch_livepatch_apply(struct livepatch_func *func) if ( is_endbr64(old_ptr) ) func->patch_offset += ENDBR64_LEN; + /* This call must be done with ->patch_offset already set. */ + len = livepatch_insn_len(func); + if ( !len ) + return; + memcpy(func->opaque, old_ptr + func->patch_offset, len); if ( func->new_addr ) { diff --git a/xen/include/xen/livepatch.h b/xen/include/xen/livepatch.h index f3ae10f007..9fdb29c382 100644 --- a/xen/include/xen/livepatch.h +++ b/xen/include/xen/livepatch.h @@ -90,7 +90,7 @@ static inline unsigned int livepatch_insn_len(const struct livepatch_func *func) { if ( !func->new_addr ) - return func->new_size; + return func->new_size - func->patch_offset; return ARCH_PATCH_INSN_SIZE; } -- generated by git-patchbot for /home/xen/git/xen.git#stable-4.14
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