This is a note to let you know that I've just added the patch titled
ftrace: Do not blindly read the ip address in ftrace_bug()
to the 5.10-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:
ftrace-do-not-blindly-read-the-ip-address-in-ftrace_bug.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6c14133d2d3f768e0a35128faac8aa6ed4815051 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
Date: Mon, 7 Jun 2021 21:39:08 -0400
Subject: ftrace: Do not blindly read the ip address in ftrace_bug()
From: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
commit 6c14133d2d3f768e0a35128faac8aa6ed4815051 upstream.
It was reported that a bug on arm64 caused a bad ip address to be used for
updating into a nop in ftrace_init(), but the error path (rightfully)
returned -EINVAL and not -EFAULT, as the bug caused more than one error to
occur. But because -EINVAL was returned, the ftrace_bug() tried to report
what was at the location of the ip address, and read it directly. This
caused the machine to panic, as the ip was not pointing to a valid memory
address.
Instead, read the ip address with copy_from_kernel_nofault() to safely
access the memory, and if it faults, report that the address faulted,
otherwise report what was in that location.
Link: https://lore.kernel.org/lkml/20210607032329.28671-1-mark-pk.tsai@xxxxxxxxxxxx/
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 05736a427f7e1 ("ftrace: warn on failure to disable mcount callers")
Reported-by: Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx>
Tested-by: Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/ftrace.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1968,12 +1968,18 @@ static int ftrace_hash_ipmodify_update(s
static void print_ip_ins(const char *fmt, const unsigned char *p)
{
+ char ins[MCOUNT_INSN_SIZE];
int i;
+ if (copy_from_kernel_nofault(ins, p, MCOUNT_INSN_SIZE)) {
+ printk(KERN_CONT "%s[FAULT] %px\n", fmt, p);
+ return;
+ }
+
printk(KERN_CONT "%s", fmt);
for (i = 0; i < MCOUNT_INSN_SIZE; i++)
- printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]);
+ printk(KERN_CONT "%s%02x", i ? ":" : "", ins[i]);
}
enum ftrace_bug_type ftrace_bug_type;
Patches currently in stable-queue which might be from rostedt@xxxxxxxxxxx are
queue-5.10/mips-fix-kernel-hang-under-function_graph_tracer-and.patch
queue-5.10/ftrace-do-not-blindly-read-the-ip-address-in-ftrace_bug.patch
