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| author | Petr Mladek <pmladek@suse.cz> | 2015-02-20 15:07:30 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-02-21 10:33:31 +0100 |
| commit | 2a6730c8b6e075adf826a89a3e2caa705807afdb (patch) | |
| tree | 05620565e26b29ba355b8241b2b80c6c0189ef52 | |
| parent | kprobes/x86: Use 5-byte NOP when the code might be modified by ftrace (diff) | |
| download | linux-2a6730c8b6e075adf826a89a3e2caa705807afdb.tar.xz linux-2a6730c8b6e075adf826a89a3e2caa705807afdb.zip | |
kprobes/x86: Check for invalid ftrace location in __recover_probed_insn()
__recover_probed_insn() should always be called from an address
where an instructions starts. The check for ftrace_location()
might help to discover a potential inconsistency.
This patch adds WARN_ON() when the inconsistency is detected.
Also it adds handling of the situation when the original code
can not get recovered.
Suggested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Petr Mladek <pmladek@suse.cz>
Cc: Ananth NMavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1424441250-27146-3-git-send-email-pmladek@suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 12 | ||||
| -rw-r--r-- | arch/x86/kernel/kprobes/opt.c | 2 |
2 files changed, 14 insertions, 0 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index c3b4b46b4797..4e3d5a9621fe 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -228,6 +228,13 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) kp = get_kprobe((void *)addr); faddr = ftrace_location(addr); /* + * Addresses inside the ftrace location are refused by + * arch_check_ftrace_location(). Something went terribly wrong + * if such an address is checked here. + */ + if (WARN_ON(faddr && faddr != addr)) + return 0UL; + /* * Use the current code if it is not modified by Kprobe * and it cannot be modified by ftrace. */ @@ -265,6 +272,7 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) * Recover the probed instruction at addr for further analysis. * Caller must lock kprobes by kprobe_mutex, or disable preemption * for preventing to release referencing kprobes. + * Returns zero if the instruction can not get recovered. */ unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) { @@ -299,6 +307,8 @@ static int can_probe(unsigned long paddr) * normally used, we just go through if there is no kprobe. */ __addr = recover_probed_instruction(buf, addr); + if (!__addr) + return 0; kernel_insn_init(&insn, (void *)__addr, MAX_INSN_SIZE); insn_get_length(&insn); @@ -347,6 +357,8 @@ int __copy_instruction(u8 *dest, u8 *src) unsigned long recovered_insn = recover_probed_instruction(buf, (unsigned long)src); + if (!recovered_insn) + return 0; kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE); insn_get_length(&insn); /* Another subsystem puts a breakpoint, failed to recover */ diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index 7c523bbf3dc8..3aef248ec1ee 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -259,6 +259,8 @@ static int can_optimize(unsigned long paddr) */ return 0; recovered_insn = recover_probed_instruction(buf, addr); + if (!recovered_insn) + return 0; kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE); insn_get_length(&insn); /* Another subsystem puts a breakpoint */ |