Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 067/262] fs/proc: fix potential unregister_sysctl_table hang | Date | Fri, 28 Sep 2012 11:49:56 -0700 |
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From: Greg KH <gregkh@linuxfoundation.org>
3.5-stable review patch. If anyone has any objections, please let me know.
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From: Francesco Ruggeri <fruggeri@aristanetworks.com>
commit 6bf6104573482570f7103d3e5ddf9574db43a363 upstream.
The unregister_sysctl_table() function hangs if all references to its ctl_table_header structure are not dropped.
This can happen sometimes because of a leak in proc_sys_lookup(): proc_sys_lookup() gets a reference to the table via lookup_entry(), but it does not release it when a subsequent call to sysctl_follow_link() fails.
This patch fixes this leak by making sure the reference is always dropped on return.
See also commit 076c3eed2c31 ("sysctl: Rewrite proc_sys_lookup introducing find_entry and lookup_entry") which reorganized this code in 3.4.
Tested in Linux 3.4.4.
Signed-off-by: Francesco Ruggeri <fruggeri@aristanetworks.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/proc/proc_sysctl.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
--- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -462,9 +462,6 @@ static struct dentry *proc_sys_lookup(st err = ERR_PTR(-ENOMEM); inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p); - if (h) - sysctl_head_finish(h); - if (!inode) goto out; @@ -473,6 +470,8 @@ static struct dentry *proc_sys_lookup(st d_add(dentry, inode); out: + if (h) + sysctl_head_finish(h); sysctl_head_finish(head); return err; }
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