From d18951834216eae82e2f9112416111b4f55f1849 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 2 May 2007 19:27:05 +0200 Subject: [PATCH] x86: Fix i386 and x86_64 fault information pollution a userspace fault or a kernelspace fault which will result in the immediate death of the process. They should not be filled in as a result of a kernelspace fault which can be fixed up. Otherwise, if the process is handling SIGSEGV and examining the fault information, this can result in the kernel space fault trashing the previously stored fault information if it arrives between the userspace fault happening and the SIGSEGV being delivered to the process. Signed-off-by: Jeff Dike Signed-off-by: Andi Kleen Acked-by: Jan Beulich -- arch/i386/kernel/traps.c | 24 ++++++++++++++++++------ arch/x86_64/kernel/traps.c | 30 +++++++++++++++++++++++------- 2 files changed, 41 insertions(+), 13 deletions(-) diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c index af0d3f7..58dfecc 100644 --- a/arch/i386/kernel/traps.c +++ b/arch/i386/kernel/traps.c @@ -476,8 +476,6 @@ static void __kprobes do_trap(int trapnr, int signr, char *str, int vm86, siginfo_t *info) { struct task_struct *tsk = current; - tsk->thread.error_code = error_code; - tsk->thread.trap_no = trapnr; if (regs->eflags & VM_MASK) { if (vm86) @@ -489,6 +487,18 @@ static void __kprobes do_trap(int trapnr, int signr, char *str, int vm86, goto kernel_trap; trap_signal: { + /* + * We want error_code and trap_no set for userspace faults and + * kernelspace faults which result in die(), but not + * kernelspace faults which are fixed up. die() gives the + * process no chance to handle the signal and notice the + * kernel fault information, so that won't result in polluting + * the information about previously queued, but not yet + * delivered, faults. See also do_general_protection below. + */ + tsk->thread.error_code = error_code; + tsk->thread.trap_no = trapnr; + if (info) force_sig_info(signr, info, tsk); else @@ -497,8 +507,11 @@ static void __kprobes do_trap(int trapnr, int signr, char *str, int vm86, } kernel_trap: { - if (!fixup_exception(regs)) + if (!fixup_exception(regs)) { + tsk->thread.error_code = error_code; + tsk->thread.trap_no = trapnr; die(str, regs, error_code); + } return; } @@ -603,9 +616,6 @@ fastcall void __kprobes do_general_protection(struct pt_regs * regs, } put_cpu(); - current->thread.error_code = error_code; - current->thread.trap_no = 13; - if (regs->eflags & VM_MASK) goto gp_in_vm86; @@ -624,6 +634,8 @@ gp_in_vm86: gp_in_kernel: if (!fixup_exception(regs)) { + current->thread.error_code = error_code; + current->thread.trap_no = 13; if (notify_die(DIE_GPF, "general protection fault", regs, error_code, 13, SIGSEGV) == NOTIFY_STOP) return; diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c index 09d2e8a..cceef5b 100644 --- a/arch/x86_64/kernel/traps.c +++ b/arch/x86_64/kernel/traps.c @@ -581,10 +581,20 @@ static void __kprobes do_trap(int trapnr, int signr, char *str, { struct task_struct *tsk = current; - tsk->thread.error_code = error_code; - tsk->thread.trap_no = trapnr; - if (user_mode(regs)) { + /* + * We want error_code and trap_no set for userspace + * faults and kernelspace faults which result in + * die(), but not kernelspace faults which are fixed + * up. die() gives the process no chance to handle + * the signal and notice the kernel fault information, + * so that won't result in polluting the information + * about previously queued, but not yet delivered, + * faults. See also do_general_protection below. + */ + tsk->thread.error_code = error_code; + tsk->thread.trap_no = trapnr; + if (exception_trace && unhandled_signal(tsk, signr)) printk(KERN_INFO "%s[%d] trap %s rip:%lx rsp:%lx error:%lx\n", @@ -605,8 +615,11 @@ static void __kprobes do_trap(int trapnr, int signr, char *str, fixup = search_exception_tables(regs->rip); if (fixup) regs->rip = fixup->fixup; - else + else { + tsk->thread.error_code = error_code; + tsk->thread.trap_no = trapnr; die(str, regs, error_code); + } return; } } @@ -682,10 +695,10 @@ asmlinkage void __kprobes do_general_protection(struct pt_regs * regs, conditional_sti(regs); - tsk->thread.error_code = error_code; - tsk->thread.trap_no = 13; - if (user_mode(regs)) { + tsk->thread.error_code = error_code; + tsk->thread.trap_no = 13; + if (exception_trace && unhandled_signal(tsk, SIGSEGV)) printk(KERN_INFO "%s[%d] general protection rip:%lx rsp:%lx error:%lx\n", @@ -704,6 +717,9 @@ asmlinkage void __kprobes do_general_protection(struct pt_regs * regs, regs->rip = fixup->fixup; return; } + + tsk->thread.error_code = error_code; + tsk->thread.trap_no = 13; if (notify_die(DIE_GPF, "general protection fault", regs, error_code, 13, SIGSEGV) == NOTIFY_STOP) return; -- cgit v0.10.2