linux-kernel - [PATCH] alpha/kernel/traps: Use find_vma_intersection() in traps for setting si

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Message-ID: <20210401195138.2895285-1-Liam.Howlett@Oracle.com>
Date:   Thu, 1 Apr 2021 19:51:48 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     Richard Henderson <rth@...ddle.net>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        Matt Turner <mattst88@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Liam Howlett <liam.howlett@...cle.com>,
        "linux-alpha@...r.kernel.org" <linux-alpha@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Dmitry Safonov <0x7f454c46@...il.com>,
        Michel Lespinasse <walken@...gle.com>,
        "Gustavo A . R . Silva" <gustavoars@...nel.org>
Subject: [PATCH] alpha/kernel/traps: Use find_vma_intersection() in traps for
 setting si_code

find_vma() will continue to search upwards until the end of the virtual
memory space.  This means the si_code would almost never be set to
SEGV_MAPERR even when the address falls outside of any VMA.

Using find_vma_intersection() allows for what is intended by only
returning a VMA if it falls within the range provided, in this case a
window of 1.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 arch/alpha/kernel/traps.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
index 921d4b6e4d95..7f51386c06d0 100644
--- a/arch/alpha/kernel/traps.c
+++ b/arch/alpha/kernel/traps.c
@@ -957,8 +957,10 @@ do_entUnaUser(void __user * va, unsigned long opcode,
 		si_code = SEGV_ACCERR;
 	else {
 		struct mm_struct *mm = current->mm;
+		unsigned long addr = (unsigned long)va;
+
 		mmap_read_lock(mm);
-		if (find_vma(mm, (unsigned long)va))
+		if (find_vma_intersection(mm, addr, addr + 1))
 			si_code = SEGV_ACCERR;
 		else
 			si_code = SEGV_MAPERR;
-- 
2.30.0