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authorVasily Averin <vvs@virtuozzo.com>2020-04-14 23:33:16 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-16 20:10:50 +0300
commit86d32f9a7c54ad74f4514d7fef7c847883207291 (patch)
tree15612f1d9e4e9c6f738085322656f648fbf795d5
parent00086336a8d96a04aa960f912287692a258f6cf5 (diff)
downloadlinux-86d32f9a7c54ad74f4514d7fef7c847883207291.tar.xz
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>
-rw-r--r--security/keys/proc.c2
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;
}