kernel/signal.c: fix kernel information leak with print-fatal-signals=1
b45c6e76 · Andi Kleen <[email protected]> · 2010-01-08 14:42:52 -08:00
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 <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
- Commit
- b45c6e76bc2c72f6426c14bed64fdcbc9bf37cb0
- Parents
- bd4f490a
Changes
1 files changed · +2 −1
diff --git a/kernel/signal.c b/kernel/signal.c
index d09692b..934ae5e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -979,7 +979,8 @@ static void print_fatal_signal(struct pt_regs *regs, int signr)
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);
}
}