https://github.com/torvalds/linux
Revision 6381c24cd6d5d6373620426ab0a96c80ed953e20 authored by Masami Hiramatsu on 17 April 2014, 08:16:44 UTC, committed by Ingo Molnar on 17 April 2014, 08:57:02 UTC
Current kprobes in-kernel page fault handler doesn't expect that its single-stepping can be interrupted by an NMI handler which may cause a page fault(e.g. perf with callback tracing). In that case, the page-fault handled by kprobes and it misunderstands the page-fault has been caused by the single-stepping code and tries to recover IP address to probed address. But the truth is the page-fault has been caused by the NMI handler, and do_page_fault failes to handle real page fault because the IP address is modified and causes Kernel BUGs like below. ---- [ 2264.726905] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 [ 2264.727190] IP: [<ffffffff813c46e0>] copy_user_generic_string+0x0/0x40 To handle this correctly, I fixed the kprobes fault handler to ensure the faulted ip address is its own single-step buffer instead of checking current kprobe state. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Sandeepa Prabhu <sandeepa.prabhu@linaro.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: fche@redhat.com Cc: systemtap@sourceware.org Link: http://lkml.kernel.org/r/20140417081644.26341.52351.stgit@ltc230.yrl.intra.hitachi.co.jp Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent 6ca2a88
Tip revision: 6381c24cd6d5d6373620426ab0a96c80ed953e20 authored by Masami Hiramatsu on 17 April 2014, 08:16:44 UTC
kprobes/x86: Fix page-fault handling logic
kprobes/x86: Fix page-fault handling logic
Tip revision: 6381c24
File | Mode | Size |
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Documentation | ||
arch | ||
block | ||
crypto | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.gitignore | -rw-r--r-- | 1.1 KB |
.mailmap | -rw-r--r-- | 4.4 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 93.6 KB |
Kbuild | -rw-r--r-- | 2.5 KB |
Kconfig | -rw-r--r-- | 252 bytes |
MAINTAINERS | -rw-r--r-- | 271.4 KB |
Makefile | -rw-r--r-- | 50.5 KB |
README | -rw-r--r-- | 18.3 KB |
REPORTING-BUGS | -rw-r--r-- | 7.3 KB |
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