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bsdacct: fix access to invalid filp in acct_on() 

The file opened in acct_on and freshly stored in the ns->bacct struct can
be closed in acct_file_reopen by a concurrent call after we release
acct_lock and before we call mntput(file->f_path.mnt).

Record file->f_path.mnt in a local variable and use this variable only.

Signed-off-by: Renaud Lottiaux <renaud.lottiaux@kerlabs.com>
Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Renaud Lottiaux 2009-06-30 11:41:34 -07:00 committed by Linus Torvalds
parent b4f90189dc
commit df279ca896
1 changed files with 4 additions and 2 deletions
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6
kernel/acct.c
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@ -215,6 +215,7 @@ static void acct_file_reopen(struct bsd_acct_struct *acct, struct file *file,
static int acct_on(char *name)
{
struct file *file;
struct vfsmount *mnt;
int error;
struct pid_namespace *ns;
struct bsd_acct_struct *acct = NULL;
@ -256,11 +257,12 @@ static int acct_on(char *name)
acct = NULL;
}
mnt_pin(file->f_path.mnt);
mnt = file->f_path.mnt;
mnt_pin(mnt);
acct_file_reopen(ns->bacct, file, ns);
spin_unlock(&acct_lock);
mntput(file->f_path.mnt); /* it's pinned, now give up active reference */
mntput(mnt); /* it's pinned, now give up active reference */
kfree(acct);
return 0;