diff mbox series

[v6,10/10] powerpc/signal: Use __get_user() to copy sigset_t

Message ID 20210221012401.22328-11-cmr@codefail.de (mailing list archive)
State Superseded
Headers show
Series Improve signal performance on PPC64 with KUAP | expand

Checks

Context Check Description
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/merge (626a6c3d2e20da80aaa710104f34ea6037b28b33)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/next (6895c5ba7bdcc55eacad03cf309ab23be63b9cac)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch linus/master (92bf22614b21a2706f4993b278017e437f7785b3)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/fixes (24321ac668e452a4942598533d267805f291fdc9)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch linux-next (1e0d27fce010b0a4a9e595506b6ede75934c31be)
snowpatch_ozlabs/apply_patch fail Failed to apply to any branch

Commit Message

Christopher M. Riedl Feb. 21, 2021, 1:24 a.m. UTC 
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>
---
 arch/powerpc/kernel/signal.h    | 7 +++++++
 arch/powerpc/kernel/signal_32.c | 2 +-
 arch/powerpc/kernel/signal_64.c | 4 ++--
 3 files changed, 10 insertions(+), 3 deletions(-)
diff mbox series

Patch

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 3dd89f99e26f..dc5bac727a62 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -707,7 +707,7 @@  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);
 
@@ -746,7 +746,7 @@  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);