* [PATCH 6.1 108/600] ARM: ptrace: Restore syscall restart tracing
[not found] <20230911134633.619970489@linuxfoundation.org>
@ 2023-09-11 13:42 ` Greg Kroah-Hartman
2023-09-11 13:42 ` [PATCH 6.1 109/600] ARM: ptrace: Restore syscall skipping for tracers Greg Kroah-Hartman
1 sibling, 0 replies; 2+ messages in thread
From: Greg Kroah-Hartman @ 2023-09-11 13:42 UTC (permalink / raw)
To: stable
Cc: Greg Kroah-Hartman, patches, Russell King, Arnd Bergmann,
Lecopzer Chen, Oleg Nesterov, linux-arm-kernel, Arnd Bergmann,
Kees Cook, Sasha Levin
6.1-stable review patch. If anyone has any objections, please let me know.
------------------
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 405a607b754f4..b413b541c3c71 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -103,6 +103,7 @@ 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)
--
2.40.1
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^ permalink raw reply related [flat|nested] 2+ messages in thread* [PATCH 6.1 109/600] ARM: ptrace: Restore syscall skipping for tracers
[not found] <20230911134633.619970489@linuxfoundation.org>
2023-09-11 13:42 ` [PATCH 6.1 108/600] ARM: ptrace: Restore syscall restart tracing Greg Kroah-Hartman
@ 2023-09-11 13:42 ` Greg Kroah-Hartman
1 sibling, 0 replies; 2+ messages in thread
From: Greg Kroah-Hartman @ 2023-09-11 13:42 UTC (permalink / raw)
To: stable
Cc: Greg Kroah-Hartman, patches, Russell King, Arnd Bergmann,
Lecopzer Chen, Oleg Nesterov, linux-arm-kernel, Arnd Bergmann,
Kees Cook, Sasha Levin
6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kees Cook <keescook@chromium.org>
[ Upstream commit 4697b5848bd933f68ebd04836362c8de0cacaf71 ]
Since commit 4e57a4ddf6b0 ("ARM: 9107/1: syscall: always store
thread_info->abi_syscall"), the seccomp selftests "syscall_errno"
and "syscall_faked" have been broken. Both seccomp and PTRACE depend
on using the special value of "-1" for skipping syscalls. This value
wasn't working because it was getting masked by __NR_SYSCALL_MASK in
both PTRACE_SET_SYSCALL and get_syscall_nr().
Explicitly test for -1 in PTRACE_SET_SYSCALL and get_syscall_nr(),
leaving it exposed when present, allowing tracers to skip syscalls
again.
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/20230810195422.2304827-2-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm/include/asm/syscall.h | 3 +++
arch/arm/kernel/ptrace.c | 5 +++--
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
index dfeed440254a8..fe4326d938c18 100644
--- a/arch/arm/include/asm/syscall.h
+++ b/arch/arm/include/asm/syscall.h
@@ -25,6 +25,9 @@ static inline int syscall_get_nr(struct task_struct *task,
if (IS_ENABLED(CONFIG_AEABI) && !IS_ENABLED(CONFIG_OABI_COMPAT))
return task_thread_info(task)->abi_syscall;
+ if (task_thread_info(task)->abi_syscall == -1)
+ return -1;
+
return task_thread_info(task)->abi_syscall & __NR_SYSCALL_MASK;
}
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index bfe88c6e60d58..cef106913ab7b 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -785,8 +785,9 @@ long arch_ptrace(struct task_struct *child, long request,
break;
case PTRACE_SET_SYSCALL:
- task_thread_info(child)->abi_syscall = data &
- __NR_SYSCALL_MASK;
+ if (data != -1)
+ data &= __NR_SYSCALL_MASK;
+ task_thread_info(child)->abi_syscall = data;
ret = 0;
break;
--
2.40.1
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^ permalink raw reply related [flat|nested] 2+ messages in thread