From 7a3f5134a8f5bd7fa38b5645eef05e8a4eb62951 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Wed, 26 Nov 2008 12:46:22 -0800 Subject: [PATCH] parisc: fix kernel crash when unwinding a userspace process Any user on existing parisc 32- and 64bit-kernels can easily crash the kernel and as such enforce a DSO. A simple testcase is available here: http://gsyprf10.external.hp.com/~deller/crash.tgz The problem is introduced by the fact, that the handle_interruption() crash handler calls the show_regs() function, which in turn tries to unwind the stack by calling parisc_show_stack(). Since the stack contains userspace addresses, a try to unwind the stack is dangerous and useless and leads to the crash. The fix is trivial: For userspace processes a) avoid to unwind the stack, and b) avoid to resolve userspace addresses to kernel symbol names. While touching this code, I converted print_symbol() to %pS printk formats and made parisc_show_stack() static. An initial patch for this was written by Kyle McMartin back in August: http://marc.info/?l=linux-parisc&m=121805168830283&w=2 Compile and run-tested with a 64bit parisc kernel. Signed-off-by: Helge Deller Cc: Grant Grundler Cc: Matthew Wilcox Cc: [2.6.25.x, 2.6.26.x, 2.6.27.x, earlier...] Signed-off-by: Andrew Morton Signed-off-by: Kyle McMartin --- arch/parisc/kernel/traps.c | 43 +++++++++++++++++++------------------- 1 file changed, 21 insertions(+), 22 deletions(-) diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c index 675f1d098f0..4c771cd580e 100644 --- a/arch/parisc/kernel/traps.c +++ b/arch/parisc/kernel/traps.c @@ -24,7 +24,6 @@ #include #include #include -#include #include #include @@ -51,7 +50,7 @@ DEFINE_SPINLOCK(pa_dbit_lock); #endif -void parisc_show_stack(struct task_struct *t, unsigned long *sp, +static void parisc_show_stack(struct task_struct *task, unsigned long *sp, struct pt_regs *regs); static int printbinary(char *buf, unsigned long x, int nbits) @@ -121,18 +120,19 @@ static void print_fr(char *level, struct pt_regs *regs) void show_regs(struct pt_regs *regs) { - int i; + int i, user; char *level; unsigned long cr30, cr31; - level = user_mode(regs) ? KERN_DEBUG : KERN_CRIT; + user = user_mode(regs); + level = user ? KERN_DEBUG : KERN_CRIT; print_gr(level, regs); for (i = 0; i < 8; i += 4) PRINTREGS(level, regs->sr, "sr", RFMT, i); - if (user_mode(regs)) + if (user) print_fr(level, regs); cr30 = mfctl(30); @@ -145,14 +145,18 @@ void show_regs(struct pt_regs *regs) printk("%s CPU: %8d CR30: " RFMT " CR31: " RFMT "\n", level, current_thread_info()->cpu, cr30, cr31); printk("%s ORIG_R28: " RFMT "\n", level, regs->orig_r28); - printk(level); - print_symbol(" IAOQ[0]: %s\n", regs->iaoq[0]); - printk(level); - print_symbol(" IAOQ[1]: %s\n", regs->iaoq[1]); - printk(level); - print_symbol(" RP(r2): %s\n", regs->gr[2]); - - parisc_show_stack(current, NULL, regs); + + if (user) { + printk("%s IAOQ[0]: " RFMT "\n", level, regs->iaoq[0]); + printk("%s IAOQ[1]: " RFMT "\n", level, regs->iaoq[1]); + printk("%s RP(r2): " RFMT "\n", level, regs->gr[2]); + } else { + printk("%s IAOQ[0]: %pS\n", level, (void *) regs->iaoq[0]); + printk("%s IAOQ[1]: %pS\n", level, (void *) regs->iaoq[1]); + printk("%s RP(r2): %pS\n", level, (void *) regs->gr[2]); + + parisc_show_stack(current, NULL, regs); + } } @@ -173,20 +177,15 @@ static void do_show_stack(struct unwind_frame_info *info) break; if (__kernel_text_address(info->ip)) { - printk("%s [<" RFMT ">] ", (i&0x3)==1 ? KERN_CRIT : "", info->ip); -#ifdef CONFIG_KALLSYMS - print_symbol("%s\n", info->ip); -#else - if ((i & 0x03) == 0) - printk("\n"); -#endif + printk(KERN_CRIT " [<" RFMT ">] %pS\n", + info->ip, (void *) info->ip); i++; } } - printk("\n"); + printk(KERN_CRIT "\n"); } -void parisc_show_stack(struct task_struct *task, unsigned long *sp, +static void parisc_show_stack(struct task_struct *task, unsigned long *sp, struct pt_regs *regs) { struct unwind_frame_info info; -- 2.41.1