Hi,
please add commit
2cf3f8133bda ("btrfs: fix lzo_decompress_bio() kmap leakage")
to the 5.15.x tree. It's been merged during the 5.16 pull, it's a fix
for a crash on 32bit architectures with enabled lzo compression.
Applies cleanly and has been tested.
Thanks.
disk->fops->owner is grabbed in blkdev_get_no_open() after the disk
kobject refcount is increased. This way can't make sure that
disk->fops->owner is still alive since del_gendisk() still can move
on if the kobject refcount of disk is grabbed by open() and ->open()
isn't called yet.
Fixes the issue by moving try_module_get() into blkdev_get_by_dev()
with ->open_mutex() held, then we can drain the in-progress open()
in del_gendisk(). Meantime new open() won't succeed because disk
becomes not alive.
This way is reasonable because blkdev_get_no_open() doesn't need
to grab disk->fops->owner which is required only if callback in
disk->fops is needed.
Cc: Christoph Hellwig <hch(a)lst.de>
Cc: stable(a)vger.kernel.org
Cc: czhong(a)redhat.com
Signed-off-by: Ming Lei <ming.lei(a)redhat.com>
---
block/bdev.c | 12 +++++++-----
block/genhd.c | 6 ++++++
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/block/bdev.c b/block/bdev.c
index b4dab2fb6a74..b1d087e5e205 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -753,8 +753,7 @@ struct block_device *blkdev_get_no_open(dev_t dev)
if (!bdev)
return NULL;
- if ((bdev->bd_disk->flags & GENHD_FL_HIDDEN) ||
- !try_module_get(bdev->bd_disk->fops->owner)) {
+ if ((bdev->bd_disk->flags & GENHD_FL_HIDDEN)) {
put_device(&bdev->bd_device);
return NULL;
}
@@ -764,7 +763,6 @@ struct block_device *blkdev_get_no_open(dev_t dev)
void blkdev_put_no_open(struct block_device *bdev)
{
- module_put(bdev->bd_disk->fops->owner);
put_device(&bdev->bd_device);
}
@@ -820,12 +818,14 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
ret = -ENXIO;
if (!disk_live(disk))
goto abort_claiming;
+ if (!try_module_get(disk->fops->owner))
+ goto abort_claiming;
if (bdev_is_partition(bdev))
ret = blkdev_get_part(bdev, mode);
else
ret = blkdev_get_whole(bdev, mode);
if (ret)
- goto abort_claiming;
+ goto put_module;
if (mode & FMODE_EXCL) {
bd_finish_claiming(bdev, holder);
@@ -847,7 +847,8 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
if (unblock_events)
disk_unblock_events(disk);
return bdev;
-
+put_module:
+ module_put(disk->fops->owner);
abort_claiming:
if (mode & FMODE_EXCL)
bd_abort_claiming(bdev, holder);
@@ -956,6 +957,7 @@ void blkdev_put(struct block_device *bdev, fmode_t mode)
blkdev_put_whole(bdev, mode);
mutex_unlock(&disk->open_mutex);
+ module_put(disk->fops->owner);
blkdev_put_no_open(bdev);
}
EXPORT_SYMBOL(blkdev_put);
diff --git a/block/genhd.c b/block/genhd.c
index a4e9e8ebd941..5f427fdc9e23 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -576,6 +576,12 @@ void del_gendisk(struct gendisk *disk)
blk_integrity_del(disk);
disk_del_events(disk);
+ /*
+ * New open() will be failed since disk becomes not alive, and old
+ * open() has either grabbed the module refcnt or been failed in
+ * case of deleting from module_exit(), so disk->fops->owner won't
+ * be unloaded if the disk is opened.
+ */
mutex_lock(&disk->open_mutex);
remove_inode_hash(disk->part0->bd_inode);
blk_drop_partitions(disk);
--
2.31.1
udf_readdir() didn't validate the directory position it should start
reading from. Thus when user uses lseek(2) on directory file descriptor
it can trick udf_readdir() into reading from a position in the middle of
directory entry which then upsets directory parsing code resulting in
errors or even possible kernel crashes. Similarly when the directory is
modified between two readdir calls, the directory position need not be
valid anymore.
Add code to validate current offset in the directory. This is actually
rather expensive for UDF as we need to read from the beginning of the
directory and parse all directory entries. This is because in UDF a
directory is just a stream of data containing directory entries and
since file names are fully under user's control we cannot depend on
detecting magic numbers and checksums in the header of directory entry
as a malicious attacker could fake them. We skip this step if we detect
that nothing changed since the last readdir call.
Reported-by: Nathan Wilson <nate(a)chickenbrittle.com>
CC: stable(a)vger.kernel.org
Signed-off-by: Jan Kara <jack(a)suse.cz>
---
fs/udf/dir.c | 32 ++++++++++++++++++++++++++++++--
fs/udf/namei.c | 3 +++
fs/udf/super.c | 2 ++
3 files changed, 35 insertions(+), 2 deletions(-)
I plan to merge this patch through my tree.
diff --git a/fs/udf/dir.c b/fs/udf/dir.c
index 70abdfad2df1..42e3e551fa4c 100644
--- a/fs/udf/dir.c
+++ b/fs/udf/dir.c
@@ -31,6 +31,7 @@
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/bio.h>
+#include <linux/iversion.h>
#include "udf_i.h"
#include "udf_sb.h"
@@ -43,7 +44,7 @@ static int udf_readdir(struct file *file, struct dir_context *ctx)
struct fileIdentDesc *fi = NULL;
struct fileIdentDesc cfi;
udf_pblk_t block, iblock;
- loff_t nf_pos;
+ loff_t nf_pos, emit_pos = 0;
int flen;
unsigned char *fname = NULL, *copy_name = NULL;
unsigned char *nameptr;
@@ -57,6 +58,7 @@ static int udf_readdir(struct file *file, struct dir_context *ctx)
int i, num, ret = 0;
struct extent_position epos = { NULL, 0, {0, 0} };
struct super_block *sb = dir->i_sb;
+ bool pos_valid = false;
if (ctx->pos == 0) {
if (!dir_emit_dot(file, ctx))
@@ -67,6 +69,21 @@ static int udf_readdir(struct file *file, struct dir_context *ctx)
if (nf_pos >= size)
goto out;
+ /*
+ * Something changed since last readdir (either lseek was called or dir
+ * changed)? We need to verify the position correctly points at the
+ * beginning of some dir entry so that the directory parsing code does
+ * not get confused. Since UDF does not have any reliable way of
+ * identifying beginning of dir entry (names are under user control),
+ * we need to scan the directory from the beginning.
+ */
+ if (!inode_eq_iversion(dir, file->f_version)) {
+ emit_pos = nf_pos;
+ nf_pos = 0;
+ } else {
+ pos_valid = true;
+ }
+
fname = kmalloc(UDF_NAME_LEN, GFP_NOFS);
if (!fname) {
ret = -ENOMEM;
@@ -122,13 +139,21 @@ static int udf_readdir(struct file *file, struct dir_context *ctx)
while (nf_pos < size) {
struct kernel_lb_addr tloc;
+ loff_t cur_pos = nf_pos;
- ctx->pos = (nf_pos >> 2) + 1;
+ /* Update file position only if we got past the current one */
+ if (nf_pos >= emit_pos) {
+ ctx->pos = (nf_pos >> 2) + 1;
+ pos_valid = true;
+ }
fi = udf_fileident_read(dir, &nf_pos, &fibh, &cfi, &epos, &eloc,
&elen, &offset);
if (!fi)
goto out;
+ /* Still not at offset where user asked us to read from? */
+ if (cur_pos < emit_pos)
+ continue;
liu = le16_to_cpu(cfi.lengthOfImpUse);
lfi = cfi.lengthFileIdent;
@@ -186,8 +211,11 @@ static int udf_readdir(struct file *file, struct dir_context *ctx)
} /* end while */
ctx->pos = (nf_pos >> 2) + 1;
+ pos_valid = true;
out:
+ if (pos_valid)
+ file->f_version = inode_query_iversion(dir);
if (fibh.sbh != fibh.ebh)
brelse(fibh.ebh);
brelse(fibh.sbh);
diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index caeef08efed2..0ed4861b038f 100644
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -30,6 +30,7 @@
#include <linux/sched.h>
#include <linux/crc-itu-t.h>
#include <linux/exportfs.h>
+#include <linux/iversion.h>
static inline int udf_match(int len1, const unsigned char *name1, int len2,
const unsigned char *name2)
@@ -134,6 +135,8 @@ int udf_write_fi(struct inode *inode, struct fileIdentDesc *cfi,
mark_buffer_dirty_inode(fibh->ebh, inode);
mark_buffer_dirty_inode(fibh->sbh, inode);
}
+ inode_inc_iversion(inode);
+
return 0;
}
diff --git a/fs/udf/super.c b/fs/udf/super.c
index b2d7c57d0688..aa2f6093d3f6 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -57,6 +57,7 @@
#include <linux/crc-itu-t.h>
#include <linux/log2.h>
#include <asm/byteorder.h>
+#include <linux/iversion.h>
#include "udf_sb.h"
#include "udf_i.h"
@@ -149,6 +150,7 @@ static struct inode *udf_alloc_inode(struct super_block *sb)
init_rwsem(&ei->i_data_sem);
ei->cached_extent.lstart = -1;
spin_lock_init(&ei->i_extent_cache_lock);
+ inode_set_iversion(&ei->vfs_inode, 1);
return &ei->vfs_inode;
}
--
2.26.2