core/entry: Respect syscall number rewrites

The transcript of the x86 entry code to the generic version failed to
reload the syscall number from ptregs after ptrace and seccomp have run,
which both can modify the syscall number in ptregs. It returns the original
syscall number instead which is obviously not the right thing to do.

Reload the syscall number to fix that.

Fixes: 142781e108 ("entry: Provide generic syscall entry functionality")
Reported-by: Kyle Huey <me@kylehuey.com> 
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kyle Huey <me@kylehuey.com> 
Tested-by: Kees Cook <keescook@chromium.org>
Acked-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/87blj6ifo8.fsf@nanos.tec.linutronix.de
This commit is contained in:
Thomas Gleixner 2020-08-19 21:44:39 +02:00
parent 9123e3a74e
commit d88d59b64c
1 changed files with 2 additions and 1 deletions

View File

@ -65,7 +65,8 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
syscall_enter_audit(regs, syscall); syscall_enter_audit(regs, syscall);
return ret ? : syscall; /* The above might have changed the syscall number */
return ret ? : syscall_get_nr(current, regs);
} }
noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall) noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)