6.4-stable review patch. If anyone has any objections, please let me know.
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From: Kees Cook keescook@chromium.org
[ Upstream commit cf007647475b5090819c5fe8da771073145c7334 ]
Since commit 4e57a4ddf6b0 ("ARM: 9107/1: syscall: always store thread_info->abi_syscall"), the seccomp selftests "syscall_restart" has been broken. This was caused by the restart syscall not being stored to "abi_syscall" during restart setup before branching to the "local_restart" label. Tracers would see the wrong syscall, and scno would get overwritten while returning from the TIF_WORK path. Add the missing store.
Cc: Russell King linux@armlinux.org.uk Cc: Arnd Bergmann arnd@kernel.org Cc: Lecopzer Chen lecopzer.chen@mediatek.com Cc: Oleg Nesterov oleg@redhat.com Cc: linux-arm-kernel@lists.infradead.org Fixes: 4e57a4ddf6b0 ("ARM: 9107/1: syscall: always store thread_info->abi_syscall") Reviewed-by: Arnd Bergmann arnd@arndb.de Link: https://lore.kernel.org/r/20230810195422.2304827-1-keescook@chromium.org Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm/kernel/entry-common.S | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 03d4c5578c5c9..b60bba3c1d516 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -90,6 +90,7 @@ slow_work_pending: cmp r0, #0 beq no_work_pending movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) + str scno, [tsk, #TI_ABI_SYSCALL] @ make sure tracers see update ldmia sp, {r0 - r6} @ have to reload r0 - r6 b local_restart @ ... and off we go ENDPROC(ret_fast_syscall)