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| author | Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> | 2017-04-11 08:08:13 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-04-27 10:09:33 +0300 |
| commit | 6c107bba66dcc696ec56482e7c07fccfb00d75c4 (patch) | |
| tree | 65f0d1366ceee32227ae653e2e4cc4a94d9ce8d5 /arch | |
| parent | 38be91ce7ea86386242a295230a517772f359df1 (diff) | |
| download | linux-6c107bba66dcc696ec56482e7c07fccfb00d75c4.tar.xz | |
powerpc/kprobe: Fix oops when kprobed on 'stdu' instruction
commit 9e1ba4f27f018742a1aa95d11e35106feba08ec1 upstream.
If we set a kprobe on a 'stdu' instruction on powerpc64, we see a kernel
OOPS:
Bad kernel stack pointer cd93c840 at c000000000009868
Oops: Bad kernel stack pointer, sig: 6 [#1]
...
GPR00: c000001fcd93cb30 00000000cd93c840 c0000000015c5e00 00000000cd93c840
...
NIP [c000000000009868] resume_kernel+0x2c/0x58
LR [c000000000006208] program_check_common+0x108/0x180
On a 64-bit system when the user probes on a 'stdu' instruction, the kernel does
not emulate actual store in emulate_step() because it may corrupt the exception
frame. So the kernel does the actual store operation in exception return code
i.e. resume_kernel().
resume_kernel() loads the saved stack pointer from memory using lwz, which only
loads the low 32-bits of the address, causing the kernel crash.
Fix this by loading the 64-bit value instead.
Fixes: be96f63375a1 ("powerpc: Split out instruction analysis part of emulate_step()")
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
[mpe: Change log massage, add stable tag]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index edba294620db..f6fd0332c3a2 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -716,7 +716,7 @@ resume_kernel: addi r8,r1,INT_FRAME_SIZE /* Get the kprobed function entry */ - lwz r3,GPR1(r1) + ld r3,GPR1(r1) subi r3,r3,INT_FRAME_SIZE /* dst: Allocate a trampoline exception frame */ mr r4,r1 /* src: current exception frame */ mr r1,r3 /* Reroute the trampoline frame to r1 */ @@ -730,8 +730,8 @@ resume_kernel: addi r6,r6,8 bdnz 2b - /* Do real store operation to complete stwu */ - lwz r5,GPR1(r1) + /* Do real store operation to complete stdu */ + ld r5,GPR1(r1) std r8,0(r5) /* Clear _TIF_EMULATE_STACK_STORE flag */ |