Re: [PATCH] arm: kgdb: fix NUMREGBYTES so that gdb_regs[] is the correct size

[Daniel Thompson]

On 06/04/18 14:25, Daniel Thompson wrote:
> On Thu, Apr 05, 2018 at 04:09:16PM -0400, David Rivshin wrote:
> > From: David Rivshin <DRivshin@xxxxxxxxxxx>
> >
> > NUMREGBYTES (which is used as the size for gdb_regs[]) is incorrectly based
> > on DBG_MAX_REG_NUM instead of GDB_MAX_REGS. DBG_MAX_REG_NUM is the number
> > of total registers, while GDB_MAX_REGS is the number of 'unsigned longs'
> > it takes to serialize those registers. Since FP registers require 3
> > 'unsigned longs' each, DBG_MAX_REG_NUM is smaller than GDB_MAX_REGS.
> >
> > This causes GDB 8.0 give the following error on connect:
> > "Truncated register 19 in remote 'g' packet"
> >
> > This also causes the register serialization/deserialization logic to
> > overflow gdb_regs[], overwriting whatever follows.
> >
> > Fixes: 834b2964b7ab ("kgdb,arm: fix register dump")
> > Cc: <stable@xxxxxxxxxxxxxxx> # 2.6.37+
> > Signed-off-by: David Rivshin <drivshin@xxxxxxxxxxx>
>
> I pointed some trivial autotests at both gdb-7.12 and gdb-8.0. Results
> look good to me!
>
> Tested-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>

BTW I noticed that myself and Jason in the only "real people" in
To: . Most arch specific patches end up making their way upstream via 
the arch maintainer rather than via the kgdb tree so personally I would 
choose to the arch maintainers in the To: field as well.

I certainly think you will have to follow up via Russell King's patch 
tracker once you think its had enough time on the ML for review.


Daniel.


> > ---
> >   arch/arm/include/asm/kgdb.h | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/include/asm/kgdb.h b/arch/arm/include/asm/kgdb.h
> > index 3b73fdcf3627a..8de1100d10674 100644
> > --- a/arch/arm/include/asm/kgdb.h
> > +++ b/arch/arm/include/asm/kgdb.h
> > @@ -77,7 +77,7 @@ extern int kgdb_fault_expected;
> >   
> >   #define KGDB_MAX_NO_CPUS	1
> >   #define BUFMAX			400
> > -#define NUMREGBYTES		(DBG_MAX_REG_NUM << 2)
> > +#define NUMREGBYTES		(GDB_MAX_REGS << 2)
> >   #define NUMCRITREGBYTES		(32 << 2)
> >   
> >   #define _R0			0
> >
> > base-commit: 0adb32858b0bddf4ada5f364a84ed60b196dbcda
> > --
> > 2.14.3