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| author | Andy Lutomirski <luto@kernel.org> | 2016-07-26 23:12:22 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-07-27 11:09:43 +0200 |
| commit | 609c19a385c8744c41f944e2a2d8afe8e8fb860e (patch) | |
| tree | 34e6a36adf4ec420dca05a5cf2c7d83c2a195ca3 /arch/x86/entry/common.c | |
| parent | 37e13a1ebe32c4fbfbdb5413f42eb6e71d8b28a4 (diff) | |
| download | lwn-609c19a385c8744c41f944e2a2d8afe8e8fb860e.tar.gz lwn-609c19a385c8744c41f944e2a2d8afe8e8fb860e.zip | |
x86/ptrace: Stop setting TS_COMPAT in ptrace code
Setting TS_COMPAT in ptrace is wrong: if we happen to do it during
syscall entry, then we'll confuse seccomp and audit. (The former
isn't a security problem: seccomp is currently entirely insecure if a
malicious ptracer is attached.) As a minimal fix, this patch adds a
new flag TS_I386_REGS_POKED that handles the ptrace special case.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5383ebed38b39fa37462139e337aff7f2314d1ca.1469599803.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry/common.c')
| -rw-r--r-- | arch/x86/entry/common.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 9e1e27d31c6d..be8c403f8117 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -270,8 +270,12 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs) * handling, because syscall restart has a fixup for compat * syscalls. The fixup is exercised by the ptrace_syscall_32 * selftest. + * + * We also need to clear TS_REGS_POKED_I386: the 32-bit tracer + * special case only applies after poking regs and before the + * very next return to user mode. */ - ti->status &= ~TS_COMPAT; + ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED); #endif user_enter_irqoff(); |