diff options
| author | Thomas Garnier <[email protected]> | 2017-06-14 18:12:02 -0700 |
|---|---|---|
| committer | Thomas Gleixner <[email protected]> | 2017-07-08 14:05:33 +0200 |
| commit | 73ac5d6a2b6ac3ae8d1e1818f3e9946f97489bc9 (patch) | |
| tree | 5d2f715c0e07a23913a64b2e42ee8cc84ce5b5e6 /arch/arm/kernel/entry-common.S | |
| parent | 5ea0727b163cb5575e36397a12eade68a1f35f24 (diff) | |
arm/syscalls: Check address limit on user-mode return
Ensure the address limit is a user-mode segment before returning to
user-mode. Otherwise a process can corrupt kernel-mode memory and
elevate privileges [1].
The set_fs function sets the TIF_SETFS flag to force a slow path on
return. In the slow path, the address limit is checked to be USER_DS if
needed.
The TIF_SETFS flag is added to _TIF_WORK_MASK shifting _TIF_SYSCALL_WORK
for arm instruction immediate support. The global work mask is too big
to used on a single instruction so adapt ret_fast_syscall.
[1] https://bugs.chromium.org/p/project-zero/issues/detail?id=990
Signed-off-by: Thomas Garnier <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: [email protected]
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: David Howells <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Miroslav Benes <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Pratyush Anand <[email protected]>
Cc: Russell King <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: [email protected]
Cc: Will Drewry <[email protected]>
Cc: [email protected]
Cc: Oleg Nesterov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Diffstat (limited to 'arch/arm/kernel/entry-common.S')
| -rw-r--r-- | arch/arm/kernel/entry-common.S | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index eb5cd77bf1d8..e33c32d56193 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -41,7 +41,9 @@ ret_fast_syscall: UNWIND(.cantunwind ) disable_irq_notrace @ disable interrupts ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing - tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK + tst r1, #_TIF_SYSCALL_WORK + bne fast_work_pending + tst r1, #_TIF_WORK_MASK bne fast_work_pending /* perform architecture specific actions before user return */ @@ -67,12 +69,15 @@ ret_fast_syscall: str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 disable_irq_notrace @ disable interrupts ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing - tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK + tst r1, #_TIF_SYSCALL_WORK + bne fast_work_pending + tst r1, #_TIF_WORK_MASK beq no_work_pending UNWIND(.fnend ) ENDPROC(ret_fast_syscall) /* Slower path - fall through to work_pending */ +fast_work_pending: #endif tst r1, #_TIF_SYSCALL_WORK |