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| author | Sven Schnelle <svens@stackframe.org> | 2021-11-13 22:41:17 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-11-21 15:46:36 +0300 |
| commit | c49bfdfe535c65fe14041cf11b7f36950f26f317 (patch) | |
| tree | 7fcd20e9334f714b00eaac8fc5a1f2babcf56dec /arch/parisc | |
| parent | b31bac061918936d6f6d647878bd45a2c81b446b (diff) | |
| download | linux-c49bfdfe535c65fe14041cf11b7f36950f26f317.tar.xz | |
parisc/entry: fix trace test in syscall exit path
commit 3ec18fc7831e7d79e2d536dd1f3bc0d3ba425e8a upstream.
commit 8779e05ba8aa ("parisc: Fix ptrace check on syscall return")
fixed testing of TI_FLAGS. This uncovered a bug in the test mask.
syscall_restore_rfi is only used when the kernel needs to exit to
usespace with single or block stepping and the recovery counter
enabled. The test however used _TIF_SYSCALL_TRACE_MASK, which
includes a lot of bits that shouldn't be tested here.
Fix this by using TIF_SINGLESTEP and TIF_BLOCKSTEP directly.
I encountered this bug by enabling syscall tracepoints. Both in qemu and
on real hardware. As soon as i enabled the tracepoint (sys_exit_read,
but i guess it doesn't really matter which one), i got random page
faults in userspace almost immediately.
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/parisc')
| -rw-r--r-- | arch/parisc/kernel/entry.S | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S index 9c76d50a5654..3da39140babc 100644 --- a/arch/parisc/kernel/entry.S +++ b/arch/parisc/kernel/entry.S @@ -1849,7 +1849,7 @@ syscall_restore: /* Are we being ptraced? */ LDREG TI_FLAGS-THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r19 - ldi _TIF_SYSCALL_TRACE_MASK,%r2 + ldi _TIF_SINGLESTEP|_TIF_BLOCKSTEP,%r2 and,COND(=) %r19,%r2,%r0 b,n syscall_restore_rfi |