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authorMaciej W. Rozycki <macro@mips.com>2017-12-11 22:53:14 +0000
committerRalf Baechle <ralf@linux-mips.org>2017-12-12 19:12:23 +0100
commit80b3ffce0196ea50068885d085ff981e4b8396f4 (patch)
tree98069b231b13d4706931c90c35ece397e0972353 /arch/mips/kernel
parentdc24d0edf33c3e15099688b6bbdf7bdc24bf6e91 (diff)
MIPS: Consistently handle buffer counter with PTRACE_SETREGSET
Update commit d614fd58a283 ("mips/ptrace: Preserve previous registers for short regset write") bug and consistently consume all data supplied to `fpr_set_msa' with the ptrace(2) PTRACE_SETREGSET request, such that a zero data buffer counter is returned where insufficient data has been given to fill a whole number of FP general registers. In reality this is not going to happen, as the caller is supposed to only supply data covering a whole number of registers and it is verified in `ptrace_regset' and again asserted in `fpr_set', however structuring code such that the presence of trailing partial FP general register data causes `fpr_set_msa' to return with a non-zero data buffer counter makes it appear that this trailing data will be used if there are subsequent writes made to FP registers, which is going to be the case with the FCSR once the missing write to that register has been fixed. Fixes: d614fd58a283 ("mips/ptrace: Preserve previous registers for short regset write") Signed-off-by: Maciej W. Rozycki <macro@mips.com> Cc: James Hogan <james.hogan@mips.com> Cc: Paul Burton <Paul.Burton@mips.com> Cc: Alex Smith <alex@alex-smith.me.uk> Cc: Dave Martin <Dave.Martin@arm.com> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v4.11+ Patchwork: https://patchwork.linux-mips.org/patch/17927/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel')
-rw-r--r--arch/mips/kernel/ptrace.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 7fcadaaf330f..47a01d5f26ea 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -504,7 +504,7 @@ static int fpr_set_msa(struct task_struct *target,
int err;
BUILD_BUG_ON(sizeof(fpr_val) != sizeof(elf_fpreg_t));
- for (i = 0; i < NUM_FPU_REGS && *count >= sizeof(elf_fpreg_t); i++) {
+ for (i = 0; i < NUM_FPU_REGS && *count > 0; i++) {
err = user_regset_copyin(pos, count, kbuf, ubuf,
&fpr_val, i * sizeof(elf_fpreg_t),
(i + 1) * sizeof(elf_fpreg_t));