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author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-10-22 10:39:47 -1000 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-10-22 10:39:47 -1000 |
commit | 5ab2ed0a8d75ce55ade89e3ff6b75bef7d9fa53f (patch) | |
tree | 3472c7283f9a3a9aa9447da187a47066d1843b44 | |
parent | 477b4e80c57f787cf8f494ccb9be23a23642b2f2 (diff) | |
parent | 964d32e512670c7b87870e30cfed2303da86d614 (diff) | |
download | linux-5ab2ed0a8d75ce55ade89e3ff6b75bef7d9fa53f.tar.bz2 |
Merge tag 'fuse-fixes-5.15-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse
Pull fuse fixes from Miklos Szeredi:
"Syzbot discovered a race in case of reusing the fuse sb (introduced in
this cycle).
Fix it by doing the s_fs_info initialization at the proper place"
* tag 'fuse-fixes-5.15-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
fuse: clean up error exits in fuse_fill_super()
fuse: always initialize sb->s_fs_info
fuse: clean up fuse_mount destruction
fuse: get rid of fuse_put_super()
fuse: check s_root when destroying sb
-rw-r--r-- | fs/fuse/fuse_i.h | 3 | ||||
-rw-r--r-- | fs/fuse/inode.c | 87 | ||||
-rw-r--r-- | fs/fuse/virtio_fs.c | 12 |
3 files changed, 46 insertions, 56 deletions
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 319596df5dc6..f55f9f94b1a4 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -1121,6 +1121,9 @@ int fuse_init_fs_context_submount(struct fs_context *fsc); */ void fuse_conn_destroy(struct fuse_mount *fm); +/* Drop the connection and free the fuse mount */ +void fuse_mount_destroy(struct fuse_mount *fm); + /** * Add connection to control filesystem */ diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 36cd03114b6d..12d49a1914e8 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -457,14 +457,6 @@ static void fuse_send_destroy(struct fuse_mount *fm) } } -static void fuse_put_super(struct super_block *sb) -{ - struct fuse_mount *fm = get_fuse_mount_super(sb); - - fuse_conn_put(fm->fc); - kfree(fm); -} - static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr) { stbuf->f_type = FUSE_SUPER_MAGIC; @@ -1003,7 +995,6 @@ static const struct super_operations fuse_super_operations = { .evict_inode = fuse_evict_inode, .write_inode = fuse_write_inode, .drop_inode = generic_delete_inode, - .put_super = fuse_put_super, .umount_begin = fuse_umount_begin, .statfs = fuse_statfs, .sync_fs = fuse_sync_fs, @@ -1424,20 +1415,17 @@ static int fuse_get_tree_submount(struct fs_context *fsc) if (!fm) return -ENOMEM; + fm->fc = fuse_conn_get(fc); fsc->s_fs_info = fm; sb = sget_fc(fsc, NULL, set_anon_super_fc); - if (IS_ERR(sb)) { - kfree(fm); + if (fsc->s_fs_info) + fuse_mount_destroy(fm); + if (IS_ERR(sb)) return PTR_ERR(sb); - } - fm->fc = fuse_conn_get(fc); /* Initialize superblock, making @mp_fi its root */ err = fuse_fill_super_submount(sb, mp_fi); if (err) { - fuse_conn_put(fc); - kfree(fm); - sb->s_fs_info = NULL; deactivate_locked_super(sb); return err; } @@ -1569,8 +1557,6 @@ static int fuse_fill_super(struct super_block *sb, struct fs_context *fsc) { struct fuse_fs_context *ctx = fsc->fs_private; int err; - struct fuse_conn *fc; - struct fuse_mount *fm; if (!ctx->file || !ctx->rootmode_present || !ctx->user_id_present || !ctx->group_id_present) @@ -1580,42 +1566,18 @@ static int fuse_fill_super(struct super_block *sb, struct fs_context *fsc) * Require mount to happen from the same user namespace which * opened /dev/fuse to prevent potential attacks. */ - err = -EINVAL; if ((ctx->file->f_op != &fuse_dev_operations) || (ctx->file->f_cred->user_ns != sb->s_user_ns)) - goto err; + return -EINVAL; ctx->fudptr = &ctx->file->private_data; - fc = kmalloc(sizeof(*fc), GFP_KERNEL); - err = -ENOMEM; - if (!fc) - goto err; - - fm = kzalloc(sizeof(*fm), GFP_KERNEL); - if (!fm) { - kfree(fc); - goto err; - } - - fuse_conn_init(fc, fm, sb->s_user_ns, &fuse_dev_fiq_ops, NULL); - fc->release = fuse_free_conn; - - sb->s_fs_info = fm; - err = fuse_fill_super_common(sb, ctx); if (err) - goto err_put_conn; + return err; /* file->private_data shall be visible on all CPUs after this */ smp_mb(); fuse_send_init(get_fuse_mount_super(sb)); return 0; - - err_put_conn: - fuse_conn_put(fc); - kfree(fm); - sb->s_fs_info = NULL; - err: - return err; } /* @@ -1637,22 +1599,40 @@ static int fuse_get_tree(struct fs_context *fsc) { struct fuse_fs_context *ctx = fsc->fs_private; struct fuse_dev *fud; + struct fuse_conn *fc; + struct fuse_mount *fm; struct super_block *sb; int err; + fc = kmalloc(sizeof(*fc), GFP_KERNEL); + if (!fc) + return -ENOMEM; + + fm = kzalloc(sizeof(*fm), GFP_KERNEL); + if (!fm) { + kfree(fc); + return -ENOMEM; + } + + fuse_conn_init(fc, fm, fsc->user_ns, &fuse_dev_fiq_ops, NULL); + fc->release = fuse_free_conn; + + fsc->s_fs_info = fm; + if (ctx->fd_present) ctx->file = fget(ctx->fd); if (IS_ENABLED(CONFIG_BLOCK) && ctx->is_bdev) { err = get_tree_bdev(fsc, fuse_fill_super); - goto out_fput; + goto out; } /* * While block dev mount can be initialized with a dummy device fd * (found by device name), normal fuse mounts can't */ + err = -EINVAL; if (!ctx->file) - return -EINVAL; + goto out; /* * Allow creating a fuse mount with an already initialized fuse @@ -1668,7 +1648,9 @@ static int fuse_get_tree(struct fs_context *fsc) } else { err = get_tree_nodev(fsc, fuse_fill_super); } -out_fput: +out: + if (fsc->s_fs_info) + fuse_mount_destroy(fm); if (ctx->file) fput(ctx->file); return err; @@ -1747,17 +1729,25 @@ static void fuse_sb_destroy(struct super_block *sb) struct fuse_mount *fm = get_fuse_mount_super(sb); bool last; - if (fm) { + if (sb->s_root) { last = fuse_mount_remove(fm); if (last) fuse_conn_destroy(fm); } } +void fuse_mount_destroy(struct fuse_mount *fm) +{ + fuse_conn_put(fm->fc); + kfree(fm); +} +EXPORT_SYMBOL(fuse_mount_destroy); + static void fuse_kill_sb_anon(struct super_block *sb) { fuse_sb_destroy(sb); kill_anon_super(sb); + fuse_mount_destroy(get_fuse_mount_super(sb)); } static struct file_system_type fuse_fs_type = { @@ -1775,6 +1765,7 @@ static void fuse_kill_sb_blk(struct super_block *sb) { fuse_sb_destroy(sb); kill_block_super(sb); + fuse_mount_destroy(get_fuse_mount_super(sb)); } static struct file_system_type fuseblk_fs_type = { diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c index 0ad89c6629d7..94fc874f5de7 100644 --- a/fs/fuse/virtio_fs.c +++ b/fs/fuse/virtio_fs.c @@ -1394,12 +1394,13 @@ static void virtio_kill_sb(struct super_block *sb) bool last; /* If mount failed, we can still be called without any fc */ - if (fm) { + if (sb->s_root) { last = fuse_mount_remove(fm); if (last) virtio_fs_conn_destroy(fm); } kill_anon_super(sb); + fuse_mount_destroy(fm); } static int virtio_fs_test_super(struct super_block *sb, @@ -1455,19 +1456,14 @@ static int virtio_fs_get_tree(struct fs_context *fsc) fsc->s_fs_info = fm; sb = sget_fc(fsc, virtio_fs_test_super, set_anon_super_fc); - if (fsc->s_fs_info) { - fuse_conn_put(fc); - kfree(fm); - } + if (fsc->s_fs_info) + fuse_mount_destroy(fm); if (IS_ERR(sb)) return PTR_ERR(sb); if (!sb->s_root) { err = virtio_fs_fill_super(sb, fsc); if (err) { - fuse_conn_put(fc); - kfree(fm); - sb->s_fs_info = NULL; deactivate_locked_super(sb); return err; } |