* [PATCH] s390/uprobes: Fix off-by-one bug in emulated PER handling
@ 2026-10-09 13:26 Heiko Carstens
2026-10-09 13:33 ` sashiko-bot
0 siblings, 1 reply; 2+ messages in thread
From: Heiko Carstens @ 2026-10-09 13:26 UTC (permalink / raw)
To: Alexander Gordeev, Sven Schnelle, Vasily Gorbik,
Christian Borntraeger
Cc: linux-kernel, linux-s390
The uprobes code emulates some instructions, and with that also
PER storage-alteration handling, in case a debugger is attached.
The PER storage-alteration handling contains an off-by-one bug, which
may lead to PER traps which should not happen. Adjust the comparison
in sim_stor_event() to fix that.
Fixes: 8d1a2427d8fc ("s390/uprobes: fix user space PER events")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
arch/s390/kernel/uprobes.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/s390/kernel/uprobes.c b/arch/s390/kernel/uprobes.c
index c624f3361e43..b2b8a377ced6 100644
--- a/arch/s390/kernel/uprobes.c
+++ b/arch/s390/kernel/uprobes.c
@@ -241,7 +241,7 @@ static void sim_stor_event(struct pt_regs *regs, void *addr, int len)
return;
if (!(current->thread.per_user.control & PER_EVENT_STORE))
return;
- if ((void *)current->thread.per_user.start > (addr + len))
+ if ((void *)current->thread.per_user.start > (addr + len - 1))
return;
if ((void *)current->thread.per_user.end < addr)
return;
--
2.53.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] s390/uprobes: Fix off-by-one bug in emulated PER handling
2026-10-09 13:26 [PATCH] s390/uprobes: Fix off-by-one bug in emulated PER handling Heiko Carstens
@ 2026-10-09 13:33 ` sashiko-bot
0 siblings, 0 replies; 2+ messages in thread
From: sashiko-bot @ 2026-10-09 13:33 UTC (permalink / raw)
To: Heiko Carstens
Cc: Heiko Carstens, linux-s390, Alexander Gordeev,
Christian Borntraeger, Vasily Gorbik
> The uprobes code emulates some instructions, and with that also
> PER storage-alteration handling, in case a debugger is attached.
>
> The PER storage-alteration handling contains an off-by-one bug, which
> may lead to PER traps which should not happen. Adjust the comparison
> in sim_stor_event() to fix that.
>
> Fixes: 8d1a2427d8fc ("s390/uprobes: fix user space PER events")
> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261009132604.2434271-1-hca@linux.ibm.com?part=1
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