Fwd: [PATCH 1/2] ARM: audit: fix treatment of saved ip register during syscall tracing

Please apply to our Fedora kernels. -------- Original Message -------- Subject: [PATCH 1/2] ARM: audit: fix treatment of saved ip register during syscall tracing Date: Fri, 4 May 2012 17:52:02 +0100 From: Will Deacon <will.deacon(a)arm.com&gt; To: patches(a)arm.linux.org.uk CC: stable(a)vger.kernel.org The ARM audit code incorrectly uses the saved application ip register value to infer syscall entry or exit. Additionally, the saved value will be clobbered if the current task is not being traced, which can lead to libc corruption if ip is live (apparently glibc uses it for the TLS pointer). This patch fixes the syscall tracing code so that the why parameter is used to infer the syscall direction and the saved ip is only updated if we know that we will be signalling a ptrace trap. Cc: stable(a)vger.kernel.org Cc: Eric Paris <eparis(a)redhat.com&gt; Reported-and-tested-by: Jon Masters <jcm(a)jonmasters.org&gt; Signed-off-by: Will Deacon <will.deacon(a)arm.com&gt; KernelVersion: 3.4-rc5 --- arch/arm/kernel/ptrace.c | 16 ++++++++-------- 1 files changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c index 80abafb..d8dbe9c 100644 --- a/arch/arm/kernel/ptrace.c +++ b/arch/arm/kernel/ptrace.c @@ -916,14 +916,7 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno) { unsigned long ip; - /* - * Save IP. IP is used to denote syscall entry/exit: - * IP = 0 -> entry, = 1 -> exit - */ - ip = regs->ARM_ip; - regs->ARM_ip = why; - - if (!ip) + if (why) audit_syscall_exit(regs); else audit_syscall_entry(AUDIT_ARCH_NR, scno, regs->ARM_r0, @@ -936,6 +929,13 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno) current_thread_info()->syscall = scno; + /* + * IP is used to denote syscall entry/exit: + * IP = 0 -> entry, =1 -> exit + */ + ip = regs->ARM_ip; + regs->ARM_ip = why; + /* the 0x80 provides a way for the tracing parent to distinguish between a syscall stop and SIGTRAP delivery */ ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html