diff options
| author | Maciej W. Rozycki <macro@mips.com> | 2017-12-11 22:52:15 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-01-17 09:38:50 +0100 |
| commit | 5b593a81fddd566aaf5f7b5f4d96ccb84b0c6148 (patch) | |
| tree | 72fa554d8a042436e0ba28d7b10ef50106f3cf27 /arch/mips/kernel/ptrace.c | |
| parent | 8eb5655aacdd9fee39a690e29252a89326c85df6 (diff) | |
MIPS: Guard against any partial write attempt with PTRACE_SETREGSET
commit dc24d0edf33c3e15099688b6bbdf7bdc24bf6e91 upstream.
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
Patchwork: https://patchwork.linux-mips.org/patch/17926/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/mips/kernel/ptrace.c')
| -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 c6df58e01418..16a7809c73be 100644 --- a/arch/mips/kernel/ptrace.c +++ b/arch/mips/kernel/ptrace.c @@ -536,7 +536,15 @@ 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, @@ -544,6 +552,8 @@ static int fpr_set(struct task_struct *target, { int err; + BUG_ON(count % sizeof(elf_fpreg_t)); + /* XXX fcr31 */ init_fp_ctx(target); |