Messages in this thread | | | Date | Tue, 28 May 2013 11:42:50 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v2] arch: arm64: kernel: sprintf(), 'str' needs additional 1 byte for failure processing |
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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@asianux.com> > --- > 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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