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authorJames Hogan <james.hogan@imgtec.com>2015-12-04 22:25:02 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-06-07 18:14:30 -0700
commitfdb691ea15b53da6854b8820df96926eb199ad2c (patch)
tree213d8a4976634e848b9c9d26c578d6b278247f48 /arch/mips/kernel
parenta8389fdf397f4c591372b13b9caa1eec4bb2b09c (diff)
MIPS: Avoid using unwind_stack() with usermode
commit 81a76d7119f63c359750e4adeff922a31ad1135f upstream. When showing backtraces in response to traps, for example crashes and address errors (usually unaligned accesses) when they are set in debugfs to be reported, unwind_stack will be used if the PC was in the kernel text address range. However since EVA it is possible for user and kernel address ranges to overlap, and even without EVA userland can still trigger an address error by jumping to a KSeg0 address. Adjust the check to also ensure that it was running in kernel mode. I don't believe any harm can come of this problem, since unwind_stack() is sufficiently defensive, however it is only meant for unwinding kernel code, so to be correct it should use the raw backtracing instead. Signed-off-by: James Hogan <james.hogan@imgtec.com> Reviewed-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/11701/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> (cherry picked from commit d2941a975ac745c607dfb590e92bb30bc352dad9) Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/mips/kernel')
-rw-r--r--arch/mips/kernel/traps.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 7322daa96bd1..99a402231f4d 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -144,7 +144,7 @@ static void show_backtrace(struct task_struct *task, const struct pt_regs *regs)
if (!task)
task = current;
- if (raw_show_trace || !__kernel_text_address(pc)) {
+ if (raw_show_trace || user_mode(regs) || !__kernel_text_address(pc)) {
show_raw_backtrace(sp);
return;
}