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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2021-06-07 21:39:08 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-06-16 11:34:54 +0200
commit0bc62e398bbd9e600959e610def5109957437b28 (patch)
treeef1ab06430b369a7ca5492823a76deba64bd7184 /kernel
parentf949bb6e67a363682a85f82797e70838d798086d (diff)
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ftrace: Do not blindly read the ip address in ftrace_bug()
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@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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/ftrace.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 93c2abe27871..e591da4449f0 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1943,12 +1943,18 @@ static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops,
static void print_ip_ins(const char *fmt, unsigned char *p)
{
+ char ins[MCOUNT_INSN_SIZE];
int i;
+ if (probe_kernel_read(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]);
}
static struct ftrace_ops *