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| author | Vasily Averin <vvs@virtuozzo.com> | 2020-04-14 21:33:16 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-16 10:10:50 -0700 |
| commit | 86d32f9a7c54ad74f4514d7fef7c847883207291 (patch) | |
| tree | 15612f1d9e4e9c6f738085322656f648fbf795d5 /security | |
| parent | 00086336a8d96a04aa960f912287692a258f6cf5 (diff) | |
| download | lwn-86d32f9a7c54ad74f4514d7fef7c847883207291.tar.gz lwn-86d32f9a7c54ad74f4514d7fef7c847883207291.zip | |
keys: Fix proc_keys_next to increase position index
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
But a read after lseek in middle of last line results in the partial
last line and then a repeat of the final line:
$ dd if=/proc/keys bs=500 skip=1
dd: /proc/keys: cannot skip to specified offset
g _uid_ses.1000: 1
3ead4096 I--Q--- 1 perm 1f3f0000 1000 65534 keyring _uid_ses.1000: 1
0+1 records in
0+1 records out
97 bytes copied, 0,000135035 s, 718 kB/s
and a read after lseek beyond end of file results in the last line being
shown:
$ 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
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
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>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security')
| -rw-r--r-- | security/keys/proc.c | 2 |
1 files changed, 2 insertions, 0 deletions
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; } |