Hello,
On Mon, May 27, 2013 at 03:00:12AM +0100, Chen Gang wrote:
>
> When failure occurs at the last looping cycle (when 'i == 0'), it will
> print "bad PC value" instead of "(%08x) ", which needs additional 1
> byte.
>
> If not add 1 byte, the 'str' may be memory overflow.
>
>
> Signed-off-by: Chen Gang <gang.chen@xxxxxxxxxxx>
> ---
> arch/arm64/kernel/traps.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index 61d7dd2..c2f68d2 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -100,7 +100,7 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
> {
> unsigned long addr = instruction_pointer(regs);
> mm_segment_t fs;
> - char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
> + char str[sizeof("00000000 ") * 5 + 2 + 1 + 1], *p = str;
> int i;
Whilst this code is difficult to follow, I don't think it's incorrect.
The size of the str array is:
sizeof("00000000 ") = 8 ('0's) + 1 (space) + 1 (NUL) = 10 bytes
*5 = 50 bytes
+2 (for the two brackets when i == 0) = 52 bytes
+1 (this is for the "bad PC value") = 53 bytes
In the worst case (when the PC is bad) we print:
"%08x " x4 = (8 + 1 + 1) *4 = 40 bytes
"bad PC value" = 12 + 1 = 13 bytes
so again, 53 bytes.
... or have I missed a character somewhere?
Will
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