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s390/entry: Fix last breaking event handling in case of stack corruption

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[ Upstream commit ae952eea6f4a7e2193f8721a5366049946e012e7 ]

In case of stack corruption stack_invalid() is called and the expectation
is that register r10 contains the last breaking event address. This
dependency is quite subtle and broke a couple of years ago without that
anybody noticed.

Fix this by getting rid of the dependency and read the last breaking event
address from lowcore.

Fixes: 56e62a7370 ("s390: convert to generic entry")
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Heiko Carstens
2025-04-24 17:07:01 +02:00
committed by Greg Kroah-Hartman
parent 2148d34371
commit 5c3b8f0575
1 changed files with 2 additions and 1 deletions
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3
arch/s390/kernel/entry.S
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@@ -636,7 +636,8 @@ SYM_CODE_START(stack_overflow)
stmg %r0,%r7,__PT_R0(%r11)
stmg %r8,%r9,__PT_PSW(%r11)
mvc __PT_R8(64,%r11),0(%r14)
stg %r10,__PT_ORIG_GPR2(%r11) # store last break to orig_gpr2
GET_LC %r2
mvc __PT_ORIG_GPR2(8,%r11),__LC_PGM_LAST_BREAK(%r2)
xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
lgr %r2,%r11 # pass pointer to pt_regs
jg kernel_stack_overflow