This is a note to let you know that I've just added the patch titled
x86/entry: Fix entry/exit mismatch on failed fast 32-bit syscalls
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-entry-fix-entry-exit-mismatch-on-failed-fast-32-bit-syscalls.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5d5675df792ff67e74a500c4c94db0f99e6a10ef Mon Sep 17 00:00:00 2001
From: Andy Lutomirski <luto@xxxxxxxxxx>
Date: Thu, 4 Mar 2021 11:05:54 -0800
Subject: x86/entry: Fix entry/exit mismatch on failed fast 32-bit syscalls
From: Andy Lutomirski <luto@xxxxxxxxxx>
commit 5d5675df792ff67e74a500c4c94db0f99e6a10ef upstream.
On a 32-bit fast syscall that fails to read its arguments from user
memory, the kernel currently does syscall exit work but not
syscall entry work. This confuses audit and ptrace. For example:
$ ./tools/testing/selftests/x86/syscall_arg_fault_32
...
strace: pid 264258: entering, ptrace_syscall_info.op == 2
...
This is a minimal fix intended for ease of backporting. A more
complete cleanup is coming.
Fixes: 0b085e68f407 ("x86/entry: Consolidate 32/64 bit syscall entry")
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/8c82296ddf803b91f8d1e5eac89e5803ba54ab0e.1614884673.git.luto@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/entry/common.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -128,7 +128,8 @@ static noinstr bool __do_fast_syscall_32
regs->ax = -EFAULT;
instrumentation_end();
- syscall_exit_to_user_mode(regs);
+ local_irq_disable();
+ irqentry_exit_to_user_mode(regs);
return false;
}
Patches currently in stable-queue which might be from luto@xxxxxxxxxx are
queue-5.10/x86-sev-es-check-regs-sp-is-trusted-before-adjusting-vc-ist-stack.patch
queue-5.10/x86-entry-fix-entry-exit-mismatch-on-failed-fast-32-bit-syscalls.patch
queue-5.10/mm-userfaultfd-fix-memory-corruption-due-to-writeprotect.patch
queue-5.10/x86-sev-es-correctly-track-irq-states-in-runtime-vc-handler.patch
