oss-security - CVE request: kernel: shm: fix shmctl(SHM_INFO) lockup with !CONFIG

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Message-ID: <28fa9c5e0903060027n5b8c3facw37516b1de21ae367@mail.gmail.com>
Date: Fri, 6 Mar 2009 16:27:39 +0800
From: Eugene Teo <eugeneteo@...nel.sg>
To: oss-security@...ts.openwall.com
Cc: "Steven M. Christey" <coley@...us.mitre.org>
Subject: CVE request: kernel: shm: fix shmctl(SHM_INFO) lockup with 
	!CONFIG_SHMEM

According to the upstream commit
a68e61e8ff2d46327a37b69056998b47745db6fa, shm_get_stat() assumes that
the inode is a "struct shmem_inode_info", which is incorrect for
!CONFIG_SHMEM (see fs/ramfs/inode.c: ramfs_get_inode() vs.
mm/shmem.c: shmem_get_inode()).

This bad assumption can cause shmctl(SHM_INFO) to lockup when
shm_get_stat() tries to spin_lock(&info->lock).  Users of
!CONFIG_SHMEM may encounter this lockup simply by invoking the 'ipcs'
command.

Reported by Jiri Olsa back in February 2008:
http://lkml.org/lkml/2008/2/29/74

Thanks, Eugene

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