From: David Howells <dhowells@redhat.com>
To: torvalds@linux-foundation.org
Cc: stable@vger.kernel.org, Vasily Averin <vvs@virtuozzo.com>,
dhowells@redhat.com, jarkko.sakkinen@linux.intel.com,
keyrings@vger.kernel.org, linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH] keys: Fix proc_keys_next to increase position index
Date: Tue, 14 Apr 2020 21:33:16 +0100 [thread overview]
Message-ID: <158689639664.3925765.4549426529245164675.stgit@warthog.procyon.org.uk> (raw)
From: Vasily Averin <vvs@virtuozzo.com>
If seq_file .next function does not change position index,
read after some lseek can generate unexpected output:
$ dd if=/proc/keys bs=1 # full usual output
0f6bfdf5 I--Q--- 2 perm 3f010000 1000 1000 user 4af2f79ab8848d0a: 740
1fb91b32 I--Q--- 3 perm 1f3f0000 1000 65534 keyring _uid.1000: 2
27589480 I--Q--- 1 perm 0b0b0000 0 0 user invocation_id: 16
2f33ab67 I--Q--- 152 perm 3f030000 0 0 keyring _ses: 2
33f1d8fa I--Q--- 4 perm 3f030000 1000 1000 keyring _ses: 1
3d427fda I--Q--- 2 perm 3f010000 1000 1000 user 69ec44aec7678e5a: 740
3ead4096 I--Q--- 1 perm 1f3f0000 1000 65534 keyring _uid_ses.1000: 1
521+0 records in
521+0 records out
521 bytes copied, 0,00123769 s, 421 kB/s
$ dd if=/proc/keys bs=500 skip=1 # read after lseek in middle of last line
dd: /proc/keys: cannot skip to specified offset
g _uid_ses.1000: 1 <<<< end of last line
3ead4096 I--Q--- 1 perm 1f3f0000 1000 65534 keyring _uid_ses.1000: 1
<<<< and whole last line again
0+1 records in
0+1 records out
97 bytes copied, 0,000135035 s, 718 kB/s
$ dd if=/proc/keys bs=1000 skip=1 # read after lseek beyond end of file
dd: /proc/keys: cannot skip to specified offset
3ead4096 I--Q--- 1 perm 1f3f0000 1000 65534 keyring _uid_ses.1000: 1
<<<< generates last line
0+1 records in
0+1 records out
76 bytes copied, 0,000119981 s, 633 kB/s
See https://bugzilla.kernel.org/show_bug.cgi?id=206283
Cc: stable@vger.kernel.org
Fixes: 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code ...")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---
security/keys/proc.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/security/keys/proc.c b/security/keys/proc.c
index 415f3f1c2da0..d0cde6685627 100644
--- a/security/keys/proc.c
+++ b/security/keys/proc.c
@@ -139,6 +139,8 @@ static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
n = key_serial_next(p, v);
if (n)
*_pos = key_node_serial(n);
+ else
+ (*_pos)++;
return n;
}
next reply other threads:[~2020-04-14 20:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 20:33 David Howells [this message]
2020-04-16 16:54 ` [PATCH] keys: Fix proc_keys_next to increase position index Jarkko Sakkinen
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