From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: David Howells <dhowells@redhat.com>
Cc: torvalds@linux-foundation.org, stable@vger.kernel.org,
Vasily Averin <vvs@virtuozzo.com>,
keyrings@vger.kernel.org, linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] keys: Fix proc_keys_next to increase position index
Date: Thu, 16 Apr 2020 19:54:32 +0300 [thread overview]
Message-ID: <20200416165432.GA199110@linux.intel.com> (raw)
In-Reply-To: <158689639664.3925765.4549426529245164675.stgit@warthog.procyon.org.uk>
On Tue, Apr 14, 2020 at 09:33:16PM +0100, David Howells wrote:
> 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
# 4.19.x
> 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>
/Jarkko
prev parent reply other threads:[~2020-04-16 16:54 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 20:33 [PATCH] keys: Fix proc_keys_next to increase position index David Howells
2020-04-16 16:54 ` Jarkko Sakkinen [this message]
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