The patch titled
kernel/signal.c: fix kernel information leak with print-fatal-signals=1
has been added to the -mm tree. Its filename is
kernel-signalc-fix-kernel-information-leak-with-print-fatal-signals=1.patch
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------------------------------------------------------
Subject: kernel/signal.c: fix kernel information leak with print-fatal-signals=1
From: Andi Kleen <andi@xxxxxxxxxxxxxx>
When print-fatal-signals is enabled it's possible to dump any memory
reachable by the kernel to the log by simply jumping to that address from
user space.
Or crash the system if there's some hardware with read side effects.
The fatal signals handler will dump 16 bytes at the execution address,
which is fully controlled by ring 3.
In addition when something jumps to a unmapped address there will be up to
16 additional useless page faults, which might be potentially slow (and at
least is not very efficient)
Fortunately this option is off by default and only there on i386.
But fix it by checking for kernel addresses and also stopping when there's
a page fault.
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/signal.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN kernel/signal.c~kernel-signalc-fix-kernel-information-leak-with-print-fatal-signals=1 kernel/signal.c
--- a/kernel/signal.c~kernel-signalc-fix-kernel-information-leak-with-print-fatal-signals=1
+++ a/kernel/signal.c
@@ -979,7 +979,8 @@ static void print_fatal_signal(struct pt
for (i = 0; i < 16; i++) {
unsigned char insn;
- __get_user(insn, (unsigned char *)(regs->ip + i));
+ if (get_user(insn, (unsigned char *)(regs->ip + i)))
+ break;
printk("%02x ", insn);
}
}
_
Patches currently in -mm which might be from andi@xxxxxxxxxxxxxx are
origin.patch
kernel-signalc-fix-kernel-information-leak-with-print-fatal-signals=1.patch
hardware-latency-detector-remove-default-m.patch
kbuild-move-fno-dwarf2-cfi-asm-to-powerpc-only.patch
mm-introduce-dump_page-and-print-symbolic-flag-names.patch
tracehooks-kill-some-pt_ptraced-checks.patch
tracehooks-check-pt_ptraced-before-reporting-the-single-step.patch
ptrace_signal-check-pt_ptraced-before-reporting-a-signal.patch
export-__ptrace_detach-and-do_notify_parent_cldstop.patch
reorder-the-code-in-kernel-ptracec.patch
implement-utrace-ptrace.patch
utrace-core.patch
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