1
0
Fork 0
mirror of https://github.com/followmsi/android_kernel_google_msm.git synced 2024-11-06 23:17:41 +00:00
android_kernel_google_msm/fs/proc
Linus Torvalds a3b4c0bace vfs,proc: guarantee unique inodes in /proc
commit 51f0885e54 upstream.

Dave Jones found another /proc issue with his Trinity tool: thanks to
the namespace model, we can have multiple /proc dentries that point to
the same inode, aliasing directories in /proc/<pid>/net/ for example.

This ends up being a total disaster, because it acts like hardlinked
directories, and causes locking problems.  We rely on the topological
sort of the inodes pointed to by dentries, and if we have aliased
directories, that odering becomes unreliable.

In short: don't do this.  Multiple dentries with the same (directory)
inode is just a bad idea, and the namespace code should never have
exposed things this way.  But we're kind of stuck with it.

This solves things by just always allocating a new inode during /proc
dentry lookup, instead of using "iget_locked()" to look up existing
inodes by superblock and number.  That actually simplies the code a bit,
at the cost of potentially doing more inode [de]allocations.

That said, the inode lookup wasn't free either (and did a lot of locking
of inodes), so it is probably not that noticeable.  We could easily keep
the old lookup model for non-directory entries, but rather than try to
be excessively clever this just implements the minimal and simplest
workaround for the problem.

Reported-and-tested-by: Dave Jones <davej@redhat.com>
Analyzed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2:
 - Adjust context
 - Never drop the pde reference in proc_get_inode(), as callers only
   expect this when we return an existing inode, and we never do that now]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Rui Xiang <rui.xiang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 10:50:30 -08:00
..
array.c procfs: fix /proc/statm 2012-03-28 17:14:35 -07:00
base.c vfs: Fix /proc/<tid>/fdinfo/<fd> file handling 2012-06-10 00:36:18 +09:00
cmdline.c
consoles.c
cpuinfo.c
devices.c
generic.c switch procfs to umode_t use 2012-01-03 22:54:56 -05:00
inode.c vfs,proc: guarantee unique inodes in /proc 2013-11-29 10:50:30 -08:00
internal.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl 2012-03-23 18:08:58 -07:00
interrupts.c
Kconfig
kcore.c fs/proc/kcore.c: make get_sparsemem_vmemmap_info() static 2012-03-23 16:58:42 -07:00
kmsg.c
loadavg.c
Makefile
meminfo.c fs/proc/meminfo.c: fix compilation error 2011-12-09 07:50:28 -08:00
mmu.c
namespaces.c fs/proc/namespaces.c: prevent crash when ns_entries[] is empty 2012-03-28 17:14:37 -07:00
nommu.c
page.c kpageflags: fix wrong KPF_THP on non-huge compound pages 2012-10-13 05:38:50 +09:00
proc_devtree.c
proc_net.c switch procfs to umode_t use 2012-01-03 22:54:56 -05:00
proc_sysctl.c fs/proc: fix potential unregister_sysctl_table hang 2012-10-02 10:29:54 -07:00
proc_tty.c
root.c proc: fix mount -t proc -o AAA 2012-04-05 15:25:50 -07:00
softirqs.c
stat.c nohz: Fix idle ticks in cpu summary line of /proc/stat 2012-10-28 10:14:12 -07:00
task_mmu.c fs/proc/task_mmu.c: fix buffer overflow in add_page_map() 2013-08-20 08:26:27 -07:00
task_nommu.c procfs: mark thread stack correctly in proc/<pid>/maps 2012-03-21 17:54:58 -07:00
uptime.c Merge branch 'sched/core' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into cputime-tip 2011-12-19 19:23:15 +01:00
version.c
vmcore.c fadump: Introduce cleanup routine to invalidate /proc/vmcore. 2012-02-23 10:50:02 +11:00