From: Joan Bruguera <joanbrugueram@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: "Joan Bruguera" <joanbrugueram@gmail.com>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH] bpf, x86: Fix IP after emitting call depth accounting
Date: Sat, 7 Jan 2023 05:14:56 +0000 [thread overview]
Message-ID: <20230107051456.8800-1-joanbrugueram@gmail.com> (raw)
Adjust the IP passed to `emit_patch` so it calculates the correct offset
for the CALL instruction if `x86_call_depth_emit_accounting` emits code.
Otherwise we will skip some instructions and most likely crash.
Fixes: b2e9dfe54be4 ("x86/bpf: Emit call depth accounting if required")
Link: https://lore.kernel.org/lkml/20230105214922.250473-1-joanbrugueram@gmail.com/
Signed-off-by: Joan Bruguera <joanbrugueram@gmail.com>
---
arch/x86/net/bpf_jit_comp.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index b808be77635e..6e696c6b7018 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -343,9 +343,10 @@ static int emit_call(u8 **pprog, void *func, void *ip)
static int emit_rsb_call(u8 **pprog, void *func, void *ip)
{
+ void *adjusted_ip;
OPTIMIZER_HIDE_VAR(func);
- x86_call_depth_emit_accounting(pprog, func);
- return emit_patch(pprog, func, ip, 0xE8);
+ adjusted_ip = (u8 *)ip + x86_call_depth_emit_accounting(pprog, func);
+ return emit_patch(pprog, func, adjusted_ip, 0xE8);
}
static int emit_jump(u8 **pprog, void *func, void *ip)
--
2.39.0
next reply other threads:[~2023-01-07 5:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-07 5:14 Joan Bruguera [this message]
2023-02-28 20:47 ` [PATCH] bpf, x86: Fix IP after emitting call depth accounting Joan Bruguera
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