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authorJann Horn <jannh@google.com>2016-06-01 12:55:06 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-06-24 20:18:20 +0300
commitdea2cf7c0c6e42ccb1eea2baba028163597bcf22 (patch)
tree3c8a6beccef08e03dfd271fdaf394e2e4c68f4e5 /fs/ecryptfs
parentd3f97524ef1b2b12df6669a701e66c02f1da523d (diff)
downloadlinux-dea2cf7c0c6e42ccb1eea2baba028163597bcf22.tar.xz
ecryptfs: forbid opening files without mmap handler
commit 2f36db71009304b3f0b95afacd8eba1f9f046b87 upstream. This prevents users from triggering a stack overflow through a recursive invocation of pagefault handling that involves mapping procfs files into virtual memory. Signed-off-by: Jann Horn <jannh@google.com> Acked-by: Tyler Hicks <tyhicks@canonical.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/ecryptfs')
-rw-r--r--fs/ecryptfs/kthread.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/fs/ecryptfs/kthread.c b/fs/ecryptfs/kthread.c
index 866bb18efefe..e818f5ac7a26 100644
--- a/fs/ecryptfs/kthread.c
+++ b/fs/ecryptfs/kthread.c
@@ -25,6 +25,7 @@
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/mount.h>
+#include <linux/file.h>
#include "ecryptfs_kernel.h"
struct ecryptfs_open_req {
@@ -147,7 +148,7 @@ int ecryptfs_privileged_open(struct file **lower_file,
flags |= IS_RDONLY(d_inode(lower_dentry)) ? O_RDONLY : O_RDWR;
(*lower_file) = dentry_open(&req.path, flags, cred);
if (!IS_ERR(*lower_file))
- goto out;
+ goto have_file;
if ((flags & O_ACCMODE) == O_RDONLY) {
rc = PTR_ERR((*lower_file));
goto out;
@@ -165,8 +166,16 @@ int ecryptfs_privileged_open(struct file **lower_file,
mutex_unlock(&ecryptfs_kthread_ctl.mux);
wake_up(&ecryptfs_kthread_ctl.wait);
wait_for_completion(&req.done);
- if (IS_ERR(*lower_file))
+ if (IS_ERR(*lower_file)) {
rc = PTR_ERR(*lower_file);
+ goto out;
+ }
+have_file:
+ if ((*lower_file)->f_op->mmap == NULL) {
+ fput(*lower_file);
+ *lower_file = NULL;
+ rc = -EMEDIUMTYPE;
+ }
out:
return rc;
}