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x86/process: Don't mix user/kernel regs in 64bit __show_regs()

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commit 9fe6299dde upstream.

When the kernel.print-fatal-signals sysctl has been enabled, a simple
userspace crash will cause the kernel to write a crash dump that contains,
among other things, the kernel gsbase into dmesg.

As suggested by Andy, limit output to pt_regs, FS_BASE and KERNEL_GS_BASE
in this case.

This also moves the bitness-specific logic from show_regs() into
process_{32,64}.c.

Fixes: 45807a1df9 ("vdso: print fatal signals")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lkml.kernel.org/r/20180831194151.123586-1-jannh@google.com
[bwh: Backported to 3.16:
 - Keep using user_mode_vm() to in 32-bit show_regs()
 - Also update call to __show_regs() in kmemcheck
 - Don't add redundant rdmsrl()s in 64-bit __show_regs()
 - Adjust filenames, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Jann Horn 2018-08-31 21:41:51 +02:00 • committed by Ben Hutchings
commit d3eb8015ec
6 changed files with 24 additions and 8 deletions
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