Commit 7e0e953bb0cf649f93277ac8fb67ecbb7f7b04a9
1 parent
0db59e5929
Exists in
ti-lsk-linux-4.1.y
and in
10 other branches
procfs: fix race between symlink removals and traversals
use_pde()/unuse_pde() in ->follow_link()/->put_link() resp. Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Showing 3 changed files with 22 additions and 12 deletions Side-by-side Diff
fs/proc/generic.c
| ... | ... | @@ -19,7 +19,6 @@ |
| 19 | 19 | #include <linux/mount.h> |
| 20 | 20 | #include <linux/init.h> |
| 21 | 21 | #include <linux/idr.h> |
| 22 | -#include <linux/namei.h> | |
| 23 | 22 | #include <linux/bitops.h> |
| 24 | 23 | #include <linux/spinlock.h> |
| 25 | 24 | #include <linux/completion.h> |
| ... | ... | @@ -222,17 +221,6 @@ |
| 222 | 221 | ida_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST); |
| 223 | 222 | spin_unlock_irqrestore(&proc_inum_lock, flags); |
| 224 | 223 | } |
| 225 | - | |
| 226 | -static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd) | |
| 227 | -{ | |
| 228 | - nd_set_link(nd, __PDE_DATA(dentry->d_inode)); | |
| 229 | - return NULL; | |
| 230 | -} | |
| 231 | - | |
| 232 | -static const struct inode_operations proc_link_inode_operations = { | |
| 233 | - .readlink = generic_readlink, | |
| 234 | - .follow_link = proc_follow_link, | |
| 235 | -}; | |
| 236 | 224 | |
| 237 | 225 | /* |
| 238 | 226 | * Don't create negative dentries here, return -ENOENT by hand |
fs/proc/inode.c
| ... | ... | @@ -23,6 +23,7 @@ |
| 23 | 23 | #include <linux/slab.h> |
| 24 | 24 | #include <linux/mount.h> |
| 25 | 25 | #include <linux/magic.h> |
| 26 | +#include <linux/namei.h> | |
| 26 | 27 | |
| 27 | 28 | #include <asm/uaccess.h> |
| 28 | 29 | |
| ... | ... | @@ -392,6 +393,26 @@ |
| 392 | 393 | .release = proc_reg_release, |
| 393 | 394 | }; |
| 394 | 395 | #endif |
| 396 | + | |
| 397 | +static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd) | |
| 398 | +{ | |
| 399 | + struct proc_dir_entry *pde = PDE(dentry->d_inode); | |
| 400 | + if (unlikely(!use_pde(pde))) | |
| 401 | + return ERR_PTR(-EINVAL); | |
| 402 | + nd_set_link(nd, pde->data); | |
| 403 | + return pde; | |
| 404 | +} | |
| 405 | + | |
| 406 | +static void proc_put_link(struct dentry *dentry, struct nameidata *nd, void *p) | |
| 407 | +{ | |
| 408 | + unuse_pde(p); | |
| 409 | +} | |
| 410 | + | |
| 411 | +const struct inode_operations proc_link_inode_operations = { | |
| 412 | + .readlink = generic_readlink, | |
| 413 | + .follow_link = proc_follow_link, | |
| 414 | + .put_link = proc_put_link, | |
| 415 | +}; | |
| 395 | 416 | |
| 396 | 417 | struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) |
| 397 | 418 | { |
fs/proc/internal.h
