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author | Maciej W. Rozycki <macro@mips.com> | 2017-12-11 22:52:15 +0000 |
---|---|---|
committer | Ralf Baechle <ralf@linux-mips.org> | 2017-12-12 19:11:53 +0100 |
commit | dc24d0edf33c3e15099688b6bbdf7bdc24bf6e91 (patch) | |
tree | d81454989e98c8925d871d8decd27aca3a0597af /arch/mips | |
parent | a03fe72572c12e98f4173f8a535f32468e48b6ec (diff) | |
download | linux-stable-dc24d0edf33c3e15099688b6bbdf7bdc24bf6e91.tar.gz linux-stable-dc24d0edf33c3e15099688b6bbdf7bdc24bf6e91.tar.bz2 linux-stable-dc24d0edf33c3e15099688b6bbdf7bdc24bf6e91.zip |
MIPS: Guard against any partial write attempt with PTRACE_SETREGSET
Complement commit d614fd58a283 ("mips/ptrace: Preserve previous
registers for short regset write") and ensure that no partial register
write attempt is made with PTRACE_SETREGSET, as we do not preinitialize
any temporaries used to hold incoming register data and consequently
random data could be written.
It is the responsibility of the caller, such as `ptrace_regset', to
arrange for writes to span whole registers only, so here we only assert
that it has indeed happened.
Signed-off-by: Maciej W. Rozycki <macro@mips.com>
Fixes: 72b22bbad1e7 ("MIPS: Don't assume 64-bit FP registers for FP regset")
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 # v3.15+
Patchwork: https://patchwork.linux-mips.org/patch/17926/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips')
-rw-r--r-- | arch/mips/kernel/ptrace.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c index 62e8ffd9370a..7fcadaaf330f 100644 --- a/arch/mips/kernel/ptrace.c +++ b/arch/mips/kernel/ptrace.c @@ -516,7 +516,15 @@ static int fpr_set_msa(struct task_struct *target, return 0; } -/* Copy the supplied NT_PRFPREG buffer to the floating-point context. */ +/* + * Copy the supplied NT_PRFPREG buffer to the floating-point context. + * + * We optimize for the case where `count % sizeof(elf_fpreg_t) == 0', + * which is supposed to have been guaranteed by the kernel before + * calling us, e.g. in `ptrace_regset'. We enforce that requirement, + * so that we can safely avoid preinitializing temporaries for + * partial register writes. + */ static int fpr_set(struct task_struct *target, const struct user_regset *regset, unsigned int pos, unsigned int count, @@ -524,6 +532,8 @@ static int fpr_set(struct task_struct *target, { int err; + BUG_ON(count % sizeof(elf_fpreg_t)); + /* XXX fcr31 */ init_fp_ctx(target); |