diff options
| -rw-r--r-- | arch/x86/kernel/traps.c | 72 |
1 files changed, 67 insertions, 5 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 05da6b5b167b..108ab1ee069f 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -56,6 +56,8 @@ #include <asm/mpx.h> #include <asm/vm86.h> #include <asm/umip.h> +#include <asm/insn.h> +#include <asm/insn-eval.h> #ifdef CONFIG_X86_64 #include <asm/x86_init.h> @@ -518,10 +520,53 @@ exit_trap: do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, 0, NULL); } -dotraplinkage void -do_general_protection(struct pt_regs *regs, long error_code) +enum kernel_gp_hint { + GP_NO_HINT, + GP_NON_CANONICAL, + GP_CANONICAL +}; + +/* + * When an uncaught #GP occurs, try to determine the memory address accessed by + * the instruction and return that address to the caller. Also, try to figure + * out whether any part of the access to that address was non-canonical. + */ +static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs, + unsigned long *addr) { - const char *desc = "general protection fault"; + u8 insn_buf[MAX_INSN_SIZE]; + struct insn insn; + + if (probe_kernel_read(insn_buf, (void *)regs->ip, MAX_INSN_SIZE)) + return GP_NO_HINT; + + kernel_insn_init(&insn, insn_buf, MAX_INSN_SIZE); + insn_get_modrm(&insn); + insn_get_sib(&insn); + + *addr = (unsigned long)insn_get_addr_ref(&insn, regs); + if (*addr == -1UL) + return GP_NO_HINT; + +#ifdef CONFIG_X86_64 + /* + * Check that: + * - the operand is not in the kernel half + * - the last byte of the operand is not in the user canonical half + */ + if (*addr < ~__VIRTUAL_MASK && + *addr + insn.opnd_bytes - 1 > __VIRTUAL_MASK) + return GP_NON_CANONICAL; +#endif + + return GP_CANONICAL; +} + +#define GPFSTR "general protection fault" + +dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) +{ + char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR; struct task_struct *tsk; RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); @@ -540,6 +585,9 @@ do_general_protection(struct pt_regs *regs, long error_code) tsk = current; if (!user_mode(regs)) { + enum kernel_gp_hint hint = GP_NO_HINT; + unsigned long gp_addr; + if (fixup_exception(regs, X86_TRAP_GP, error_code, 0)) return; @@ -556,8 +604,22 @@ do_general_protection(struct pt_regs *regs, long error_code) return; if (notify_die(DIE_GPF, desc, regs, error_code, - X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP) - die(desc, regs, error_code); + X86_TRAP_GP, SIGSEGV) == NOTIFY_STOP) + return; + + if (error_code) + snprintf(desc, sizeof(desc), "segment-related " GPFSTR); + else + hint = get_kernel_gp_address(regs, &gp_addr); + + if (hint != GP_NO_HINT) + snprintf(desc, sizeof(desc), GPFSTR ", %s 0x%lx", + (hint == GP_NON_CANONICAL) ? + "probably for non-canonical address" : + "maybe for address", + gp_addr); + + die(desc, regs, error_code); return; } |