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From:   Andreas Schwab <schwab@suse.de>
To:     linux-riscv@lists.infradead.org
Subject: [PATCH] riscv: fix locking violation in page fault handler
CC:     linux-kernel@vger.kernel.org
Date:   Tue, 07 May 2019 09:36:46 +0200
Message-ID: <mvm5zqmu35d.fsf@suse.de>
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When a user mode process accesses an address in the vmalloc area
do_page_fault tries to unlock the mmap semaphore when it isn't locked.

Signed-off-by: Andreas Schwab <schwab@suse.de>
---
 arch/riscv/mm/fault.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 88401d5125bc..c51878e5a66a 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -181,6 +181,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
 	up_read(&mm->mmap_sem);
 	/* User mode accesses just cause a SIGSEGV */
 	if (user_mode(regs)) {
+bad_area_do_trap:
 		do_trap(regs, SIGSEGV, code, addr, tsk);
 		return;
 	}
@@ -230,7 +231,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
 		int index;
 
 		if (user_mode(regs))
-			goto bad_area;
+			goto bad_area_do_trap;
 
 		/*
 		 * Synchronize this task's top level page-table
-- 
2.21.0


-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."