Messages in this thread Patch in this message | | | Date | Fri, 13 Aug 2010 14:42:58 -0700 | From | Greg KH <> | Subject | [3/3] x86: dont send SIGBUS for kernel page faults |
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2.6.27-stable review patch. If anyone has any objections, please let us know.
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Based on commit 96054569190bdec375fe824e48ca1f4e3b53dd36 upstream, authored by Linus Torvalds.
This is my backport to the .27 kernel tree, hopefully preserving the same functionality.
Original commit message: It's wrong for several reasons, but the most direct one is that the fault may be for the stack accesses to set up a previous SIGBUS. When we have a kernel exception, the kernel exception handler does all the fixups, not some user-level signal handler.
Even apart from the nested SIGBUS issue, it's also wrong to give out kernel fault addresses in the signal handler info block, or to send a SIGBUS when a system call already returns EFAULT.
Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- arch/x86/mm/fault.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -589,6 +589,7 @@ void __kprobes do_page_fault(struct pt_r unsigned long address; int write, si_code; int fault; + int should_exit_no_context = 0; #ifdef CONFIG_X86_64 unsigned long flags; #endif @@ -876,6 +877,9 @@ no_context: oops_end(flags, regs, SIGKILL); #endif + if (should_exit_no_context) + return; + /* * We ran out of memory, or some other thing happened to us that made * us unable to handle the page fault gracefully. @@ -901,8 +905,11 @@ do_sigbus: up_read(&mm->mmap_sem); /* Kernel mode? Handle exceptions or die */ - if (!(error_code & PF_USER)) + if (!(error_code & PF_USER)) { + should_exit_no_context = 1; goto no_context; + } + #ifdef CONFIG_X86_32 /* User space => ok to do another page fault */ if (is_prefetch(regs, address, error_code))
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