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| author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2021-06-07 21:39:08 -0400 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2021-06-08 16:44:00 -0400 |
| commit | 6c14133d2d3f768e0a35128faac8aa6ed4815051 (patch) | |
| tree | 0e167a71dda06575dfe90278df847fd8430de508 /kernel | |
| parent | 824afd55e95c3cb12c55d297a0ae408be1779cc8 (diff) | |
| download | linux-6c14133d2d3f768e0a35128faac8aa6ed4815051.tar.gz linux-6c14133d2d3f768e0a35128faac8aa6ed4815051.tar.bz2 linux-6c14133d2d3f768e0a35128faac8aa6ed4815051.zip | |
ftrace: Do not blindly read the ip address in ftrace_bug()
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@mediatek.com/
Cc: stable@vger.kernel.org
Fixes: 05736a427f7e1 ("ftrace: warn on failure to disable mcount callers")
Reported-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Tested-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/ftrace.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 2e8a3fde7104..72ef4dccbcc4 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1967,12 +1967,18 @@ static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops, 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; |