* [PATCH] powerpc/signal32: Fix erroneous SIGSEGV on RT signal return
@ 2021-04-23 13:52 Christophe Leroy
2021-04-29 14:01 ` Michael Ellerman
0 siblings, 1 reply; 2+ messages in thread
From: Christophe Leroy @ 2021-04-23 13:52 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman
Cc: linux-kernel, linuxppc-dev
Return of user_read_access_begin() is tested the wrong way,
leading to a SIGSEGV when the user address is valid and likely
an Oops when the user address is bad.
Fix the test.
Fixes: 887f3ceb51cd ("powerpc/signal32: Convert do_setcontext[_tm]() to user access block")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/signal_32.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index fc41c58f0cbb..8f05ed0da292 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -967,7 +967,7 @@ static int do_setcontext(struct ucontext __user *ucp, struct pt_regs *regs, int
sigset_t set;
struct mcontext __user *mcp;
- if (user_read_access_begin(ucp, sizeof(*ucp)))
+ if (!user_read_access_begin(ucp, sizeof(*ucp)))
return -EFAULT;
unsafe_get_sigset_t(&set, &ucp->uc_sigmask, failed);
@@ -1005,7 +1005,7 @@ static int do_setcontext_tm(struct ucontext __user *ucp,
u32 cmcp;
u32 tm_cmcp;
- if (user_read_access_begin(ucp, sizeof(*ucp)))
+ if (!user_read_access_begin(ucp, sizeof(*ucp)))
return -EFAULT;
unsafe_get_sigset_t(&set, &ucp->uc_sigmask, failed);
--
2.25.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] powerpc/signal32: Fix erroneous SIGSEGV on RT signal return
2021-04-23 13:52 [PATCH] powerpc/signal32: Fix erroneous SIGSEGV on RT signal return Christophe Leroy
@ 2021-04-29 14:01 ` Michael Ellerman
0 siblings, 0 replies; 2+ messages in thread
From: Michael Ellerman @ 2021-04-29 14:01 UTC (permalink / raw)
To: Michael Ellerman, Benjamin Herrenschmidt, Christophe Leroy,
Paul Mackerras
Cc: linux-kernel, linuxppc-dev
On Fri, 23 Apr 2021 13:52:10 +0000 (UTC), Christophe Leroy wrote:
> Return of user_read_access_begin() is tested the wrong way,
> leading to a SIGSEGV when the user address is valid and likely
> an Oops when the user address is bad.
>
> Fix the test.
Applied to powerpc/next.
[1/1] powerpc/signal32: Fix erroneous SIGSEGV on RT signal return
https://git.kernel.org/powerpc/c/5256426247837feb8703625bda7fcfc824af04cf
cheers
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