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[tip:,x86/urgent] x86/entry: Fix entry/exit mismatch on failed fast 32-bit syscalls

Message ID 161493937508.398.8936209544992148886.tip-bot2@tip-bot2
State New
Headers show
Series [tip:,x86/urgent] x86/entry: Fix entry/exit mismatch on failed fast 32-bit syscalls | expand

Commit Message

thermal-bot for Julien Panis March 5, 2021, 10:16 a.m. UTC
The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     dabf017539988a9bfc40a38dbafd35c501bacc44
Gitweb:        https://git.kernel.org/tip/dabf017539988a9bfc40a38dbafd35c501bacc44
Author:        Andy Lutomirski <luto@kernel.org>
AuthorDate:    Thu, 04 Mar 2021 11:05:54 -08:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Fri, 05 Mar 2021 11:10:13 +01:00

x86/entry: Fix entry/exit mismatch on failed fast 32-bit syscalls

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@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/8c82296ddf803b91f8d1e5eac89e5803ba54ab0e.1614884673.git.luto@kernel.org

---
 arch/x86/entry/common.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
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Patch

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index a2433ae..4efd39a 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -128,7 +128,8 @@  static noinstr bool __do_fast_syscall_32(struct pt_regs *regs)
 		regs->ax = -EFAULT;
 
 		instrumentation_end();
-		syscall_exit_to_user_mode(regs);
+		local_irq_disable();
+		irqentry_exit_to_user_mode(regs);
 		return false;
 	}