[PATCH] arm64: ptrace: fix empty registers set in prstatus of aarch32 process core
Will Deacon
will.deacon at arm.com
Tue Jun 3 07:46:02 PDT 2014
Hi Victor,
Thanks for both the fix and the detailed explanation!
On Tue, Jun 03, 2014 at 06:46:09AM +0100, Victor Kamensky wrote:
> Currently core file of aarch32 process prstatus note has empty
> registers set. As result aarch32 core files create by V8 kernel are
> not very useful.
>
> It happens because compat_gpr_get and compat_gpr_set functions can
> copy registers values to/from either kbuf or ubuf. ELF core file
> collection function fill_thread_core_info calls compat_gpr_get
> with kbuf set and ubuf set to 0. But current compat_gpr_get and
> compat_gpr_set function handle copy to/from only ubuf case.
>
> Fix is to handle kbuf and ubuf as two separate cases in similar
> way as other functions like user_regset_copyout, user_regset_copyin do.
An alternative is to use set_fs when kbuf is set, then use
copy_{to,from}_user for everything. However, given how ugly I find
set_fs to start with, your patch looks good to me:
Acked-by: Will Deacon <will.deacon at arm.com>
We probably want a CC stable too.
Cheers,
Will
> Signed-off-by: Victor Kamensky <victor.kamensky at linaro.org>
> ---
> arch/arm64/kernel/ptrace.c | 28 +++++++++++++++++++---------
> 1 file changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> index 6a8928b..9c9c2b9 100644
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -650,11 +650,16 @@ static int compat_gpr_get(struct task_struct *target,
> reg = task_pt_regs(target)->regs[idx];
> }
>
> - ret = copy_to_user(ubuf, ®, sizeof(reg));
> - if (ret)
> - break;
> -
> - ubuf += sizeof(reg);
> + if (kbuf) {
> + memcpy(kbuf, ®, sizeof(reg));
> + kbuf += sizeof(reg);
> + } else {
> + ret = copy_to_user(ubuf, ®, sizeof(reg));
> + if (ret)
> + break;
> +
> + ubuf += sizeof(reg);
> + }
> }
>
> return ret;
> @@ -684,11 +689,16 @@ static int compat_gpr_set(struct task_struct *target,
> unsigned int idx = start + i;
> compat_ulong_t reg;
>
> - ret = copy_from_user(®, ubuf, sizeof(reg));
> - if (ret)
> - return ret;
> + if (kbuf) {
> + memcpy(®, kbuf, sizeof(reg));
> + kbuf += sizeof(reg);
> + } else {
> + ret = copy_from_user(®, ubuf, sizeof(reg));
> + if (ret)
> + return ret;
>
> - ubuf += sizeof(reg);
> + ubuf += sizeof(reg);
> + }
>
> switch (idx) {
> case 15:
> --
> 1.8.1.4
>
>
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