| [PATCH -mm] Fix race between proc_readdir and remove_proc_entry [message #11045] |
Sun, 11 March 2007 11:52 |
Alexey Dobriyan
Messages: 195
Registered: August 2006
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Senior Member |
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> -procfs-fix-race-between-proc_readdir-and-remove_proc_entry. patch
> +fix-race-between-proc_get_inode-and-remove_proc_entry.patch
>
> Updated. Looks sane.
Why have you dropped the first patch? Resending slightly fixed version
of it.
[PATCH -mm] Fix race between proc_readdir and remove_proc_entry
From: "Darrick J. Wong" <djwong@us.ibm.com>
Fix the following race:
proc_readdir remove_proc_entry
============ =================
spin_lock(&proc_subdir_lock);
[choose PDE to start filldir from]
spin_unlock(&proc_subdir_lock);
spin_lock(&proc_subdir_lock);
[find PDE]
[free PDE, refcount is 0]
spin_unlock(&proc_subdir_lock);
/* boom */
if (filldir(dirent, de->name, ...
[de_put on error path --adobriyan]
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
---
fs/proc/generic.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -478,14 +478,21 @@ int proc_readdir(struct file * filp,
}
do {
+ struct proc_dir_entry *next;
+
/* filldir passes info to user space */
+ de_get(de);
spin_unlock(&proc_subdir_lock);
if (filldir(dirent, de->name, de->namelen, filp->f_pos,
- de->low_ino, de->mode >> 12) < 0)
+ de->low_ino, de->mode >> 12) < 0) {
+ de_put(de);
goto out;
+ }
spin_lock(&proc_subdir_lock);
filp->f_pos++;
- de = de->next;
+ next = de->next;
+ de_put(de);
+ de = next;
} while (de);
spin_unlock(&proc_subdir_lock);
}
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