From: Jinyang He <hejinyang@loongson.cn>
To: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] MIPS: Fix strnlen_user access check
Date: Sun, 11 Apr 2021 19:04:52 +0800 [thread overview]
Message-ID: <1618139092-4018-1-git-send-email-hejinyang@loongson.cn> (raw)
Commit 04324f44cb69 ("MIPS: Remove get_fs/set_fs") brought a problem for
strnlen_user(). Jump out when checking access_ok() with condition that
(s + strlen(s)) < __UA_LIMIT <= (s + n). The old __strnlen_user_asm()
just checked (ua_limit & s) without checking (ua_limit & (s + n)).
Therefore, find strlen form s to __UA_LIMIT - 1 in that condition.
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
arch/mips/include/asm/uaccess.h | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index 91bc7fb..85ba0c8 100644
--- a/arch/mips/include/asm/uaccess.h
+++ b/arch/mips/include/asm/uaccess.h
@@ -630,8 +630,15 @@ static inline long strnlen_user(const char __user *s, long n)
{
long res;
- if (!access_ok(s, n))
- return -0;
+ if (unlikely(n <= 0))
+ return 0;
+
+ if (!access_ok(s, n)) {
+ if (!access_ok(s, 0))
+ return 0;
+
+ n = __UA_LIMIT - (unsigned long)s - 1;
+ }
might_fault();
__asm__ __volatile__(
--
2.1.0
next reply other threads:[~2021-04-11 11:05 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-11 11:04 Jinyang He [this message]
2021-04-12 3:02 ` [PATCH] MIPS: Fix strnlen_user access check Tiezhu Yang
2021-04-12 6:06 ` Jinyang He
2021-04-12 7:08 ` Tiezhu Yang
2021-04-12 14:27 ` Thomas Bogendoerfer
2021-04-13 1:15 ` Jinyang He
2021-04-13 8:34 ` David Laight
2021-04-13 11:14 ` Thomas Bogendoerfer
2021-04-13 12:37 ` David Laight
2021-04-13 15:19 ` Thomas Bogendoerfer
2021-04-13 16:01 ` David Laight
2021-04-14 7:59 ` Thomas Bogendoerfer
2021-04-12 13:47 ` Jinyang He
2021-04-15 21:26 Thomas Bogendoerfer
2021-04-16 7:22 ` Thomas Bogendoerfer
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