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| author | Fredrik Strupe <fredrik@strupe.net> | 2020-05-18 21:41:11 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-06-20 11:24:08 +0300 |
| commit | d95c626d0b89ddbd223d210cafa07b38e53d9898 (patch) | |
| tree | 06016134105fd22b807d0d8f8868415b352656ce /arch/arm | |
| parent | adbbd088ab97077fa0529740ec43185c7fb7cdd5 (diff) | |
| download | linux-d95c626d0b89ddbd223d210cafa07b38e53d9898.tar.xz | |
ARM: 8977/1: ptrace: Fix mask for thumb breakpoint hook
[ Upstream commit 3866f217aaa81bf7165c7f27362eee5d7919c496 ]
call_undef_hook() in traps.c applies the same instr_mask for both 16-bit
and 32-bit thumb instructions. If instr_mask then is only 16 bits wide
(0xffff as opposed to 0xffffffff), the first half-word of 32-bit thumb
instructions will be masked out. This makes the function match 32-bit
thumb instructions where the second half-word is equal to instr_val,
regardless of the first half-word.
The result in this case is that all undefined 32-bit thumb instructions
with the second half-word equal to 0xde01 (udf #1) work as breakpoints
and will raise a SIGTRAP instead of a SIGILL, instead of just the one
intended 16-bit instruction. An example of such an instruction is
0xeaa0de01, which is unallocated according to Arm ARM and should raise a
SIGILL, but instead raises a SIGTRAP.
This patch fixes the issue by setting all the bits in instr_mask, which
will still match the intended 16-bit thumb instruction (where the
upper half is always 0), but not any 32-bit thumb instructions.
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Fredrik Strupe <fredrik@strupe.net>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/kernel/ptrace.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c index ae738a6319f6..364985c96a92 100644 --- a/arch/arm/kernel/ptrace.c +++ b/arch/arm/kernel/ptrace.c @@ -227,8 +227,8 @@ static struct undef_hook arm_break_hook = { }; static struct undef_hook thumb_break_hook = { - .instr_mask = 0xffff, - .instr_val = 0xde01, + .instr_mask = 0xffffffff, + .instr_val = 0x0000de01, .cpsr_mask = PSR_T_BIT, .cpsr_val = PSR_T_BIT, .fn = break_trap, |