From 117ceeb1f4f87331e45a77e71f18303d15ec882e Mon Sep 17 00:00:00 2001 From: Stephane Eranian Date: Wed, 28 Sep 2022 11:40:42 -0700 Subject: [PATCH] perf/x86/utils: Fix uninitialized var in get_branch_type() offset is passed as a pointer and on certain call path is not set by the function. If the caller does not re-initialize offset between calls, value could be inherited between calls. Prevent this by initializing offset on each call. This impacts the code in amd_pmu_lbr_filter() which does: for(i=0; ...) { ret = get_branch_type_fused(..., &offset); if (offset) lbr_entries[i].from += offset; } Fixes: df3e9612f758 ("perf/x86: Make branch classifier fusion-aware") Signed-off-by: Stephane Eranian Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Sandipan Das Link: https://lore.kernel.org/r/20220928184043.408364-2-eranian@google.com --- arch/x86/events/utils.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/events/utils.c b/arch/x86/events/utils.c index 5f5617afde79..76b1f8bb0fd5 100644 --- a/arch/x86/events/utils.c +++ b/arch/x86/events/utils.c @@ -94,6 +94,10 @@ static int get_branch_type(unsigned long from, unsigned long to, int abort, u8 buf[MAX_INSN_SIZE]; int is64 = 0; + /* make sure we initialize offset */ + if (offset) + *offset = 0; + to_plm = kernel_ip(to) ? X86_BR_KERNEL : X86_BR_USER; from_plm = kernel_ip(from) ? X86_BR_KERNEL : X86_BR_USER;