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| author | Christopher M. Riedl <cmr@codefail.de> | 2021-02-26 19:12:59 -0600 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-03-29 12:52:24 +1100 |
| commit | d3ccc9781560af051554017c702631560bdc0811 (patch) | |
| tree | 3b6184e4a3457313d93a968f4b27474294143349 | |
| parent | 0f92433b8f9f76608528101e7a81cd3bfd00e236 (diff) | |
| download | lwn-d3ccc9781560af051554017c702631560bdc0811.tar.gz lwn-d3ccc9781560af051554017c702631560bdc0811.zip | |
powerpc/signal: Use __get_user() to copy sigset_t
Usually sigset_t is exactly 8B which is a "trivial" size and does not
warrant using __copy_from_user(). Use __get_user() directly in
anticipation of future work to remove the trivial size optimizations
from __copy_from_user().
The ppc32 implementation of get_sigset_t() previously called
copy_from_user() which, unlike __copy_from_user(), calls access_ok().
Replacing this w/ __get_user() (no access_ok()) is fine here since both
callsites in signal_32.c are preceded by an earlier access_ok().
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-11-cmr@codefail.de
| -rw-r--r-- | arch/powerpc/kernel/signal.h | 7 | ||||
| -rw-r--r-- | arch/powerpc/kernel/signal_32.c | 2 | ||||
| -rw-r--r-- | arch/powerpc/kernel/signal_64.c | 4 |
3 files changed, 10 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/signal.h b/arch/powerpc/kernel/signal.h index d8dd76b1dc94..1393876f3814 100644 --- a/arch/powerpc/kernel/signal.h +++ b/arch/powerpc/kernel/signal.h @@ -19,6 +19,13 @@ extern int handle_signal32(struct ksignal *ksig, sigset_t *oldset, extern int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset, struct task_struct *tsk); +static inline int __get_user_sigset(sigset_t *dst, const sigset_t __user *src) +{ + BUILD_BUG_ON(sizeof(sigset_t) != sizeof(u64)); + + return __get_user(dst->sig[0], (u64 __user *)&src->sig[0]); +} + #ifdef CONFIG_VSX extern unsigned long copy_vsx_to_user(void __user *to, struct task_struct *task); diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index 75ee918a120a..c505b444a613 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -144,7 +144,7 @@ static inline int restore_general_regs(struct pt_regs *regs, static inline int get_sigset_t(sigset_t *set, const sigset_t __user *uset) { - return copy_from_user(set, uset, sizeof(*uset)); + return __get_user_sigset(set, uset); } #define to_user_ptr(p) ((unsigned long)(p)) diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index e7d612e82363..e10459f11f8e 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -708,7 +708,7 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx, * We kill the task with a SIGSEGV in this situation. */ - if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set))) + if (__get_user_sigset(&set, &new_ctx->uc_sigmask)) do_exit(SIGSEGV); set_current_blocked(&set); @@ -747,7 +747,7 @@ SYSCALL_DEFINE0(rt_sigreturn) if (!access_ok(uc, sizeof(*uc))) goto badframe; - if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set))) + if (__get_user_sigset(&set, &uc->uc_sigmask)) goto badframe; set_current_blocked(&set); |