[PATCH 0/1] s390: seq_file .next functions should increase position index

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



In Aug 2018 NeilBrown noticed 
commit 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code and interface")
"Some ->next functions do not increment *pos when they return NULL...
Note that such ->next functions are buggy and should be fixed. 
A simple demonstration is
   
dd if=/proc/swaps bs=1000 skip=1
    
Choose any block size larger than the size of /proc/swaps.  This will
always show the whole last line of /proc/swaps"

Described problem is still actual. If you make lseek into middle of last output line 
following read will output end of last line and whole last line once again.

$ dd if=/proc/swaps bs=1  # usual output
Filename				Type		Size	Used	Priority
/dev/dm-0                               partition	4194812	97536	-2
104+0 records in
104+0 records out
104 bytes copied

$ dd if=/proc/swaps bs=40 skip=1    # last line was generated twice
dd: /proc/swaps: cannot skip to specified offset
v/dm-0                               partition	4194812	97536	-2
/dev/dm-0                               partition	4194812	97536	-2 
3+1 records in
3+1 records out
131 bytes copied

There are lot of other affected files, I've found 30+ including
/proc/net/ip_tables_matches and /proc/sysvipc/*

Following patch fixes s390-related file

https://bugzilla.kernel.org/show_bug.cgi?id=206283

Vasily Averin (1):
  cio_ignore_proc_seq_next should increase position index

 drivers/s390/cio/blacklist.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

-- 
1.8.3.1




[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Kernel Development]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite Info]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Samba]     [Linux Media]     [Device Mapper]

  Powered by Linux