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Date: Fri, 2 Feb 2024 13:40:45 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Cc: Kees Cook <keescook@...omium.org>,
Nathan Chancellor <nathan@...nel.org>,
Steve French <sfrench@...ba.org>,
Paulo Alcantara <pc@...guebit.com>,
Ronnie Sahlberg <ronniesahlberg@...il.com>,
Shyam Prasad N <sprasad@...rosoft.com>,
Tom Talpey <tom@...pey.com>,
linux-cifs@...r.kernel.org,
llvm@...ts.linux.dev,
Steve French <stfrench@...rosoft.com>,
Sasha Levin <sashal@...nel.org>,
samba-technical@...ts.samba.org
Subject: [PATCH AUTOSEL 6.1 08/15] smb: Work around Clang __bdos() type confusion
From: Kees Cook <keescook@...omium.org>
[ Upstream commit 8deb05c84b63b4fdb8549e08942867a68924a5b8 ]
Recent versions of Clang gets confused about the possible size of the
"user" allocation, and CONFIG_FORTIFY_SOURCE ends up emitting a
warning[1]:
repro.c:126:4: warning: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
126 | __write_overflow_field(p_size_field, size);
| ^
for this memset():
int len;
__le16 *user;
...
len = ses->user_name ? strlen(ses->user_name) : 0;
user = kmalloc(2 + (len * 2), GFP_KERNEL);
...
if (len) {
...
} else {
memset(user, '\0', 2);
}
While Clang works on this bug[2], switch to using a direct assignment,
which avoids memset() entirely which both simplifies the code and silences
the false positive warning. (Making "len" size_t also silences the
warning, but the direct assignment seems better.)
Reported-by: Nathan Chancellor <nathan@...nel.org>
Closes: https://github.com/ClangBuiltLinux/linux/issues/1966 [1]
Link: https://github.com/llvm/llvm-project/issues/77813 [2]
Cc: Steve French <sfrench@...ba.org>
Cc: Paulo Alcantara <pc@...guebit.com>
Cc: Ronnie Sahlberg <ronniesahlberg@...il.com>
Cc: Shyam Prasad N <sprasad@...rosoft.com>
Cc: Tom Talpey <tom@...pey.com>
Cc: linux-cifs@...r.kernel.org
Cc: llvm@...ts.linux.dev
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
fs/smb/client/cifsencrypt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/smb/client/cifsencrypt.c b/fs/smb/client/cifsencrypt.c
index d0ac2648c0d6..d3d4cf6321fd 100644
--- a/fs/smb/client/cifsencrypt.c
+++ b/fs/smb/client/cifsencrypt.c
@@ -444,7 +444,7 @@ static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
len = cifs_strtoUTF16(user, ses->user_name, len, nls_cp);
UniStrupr(user);
} else {
- memset(user, '\0', 2);
+ *(u16 *)user = 0;
}
rc = crypto_shash_update(ses->server->secmech.hmacmd5,
--
2.43.0
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