Messages in this thread | | | Subject | Re: [PATCH -next] jffs2: fix use-after-free in jffs2_clear_xattr_subsystem | From | "libaokun (A)" <> | Date | Fri, 18 Feb 2022 14:12:58 +0800 |
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在 2021/12/28 20:54, Baokun Li 写道:
ping
> When we mount a jffs2 image, assume that the first few blocks of > the image are normal and contain at least one xattr-related inode, > but the next block is abnormal. As a result, an error is returned > in jffs2_scan_eraseblock(). jffs2_clear_xattr_subsystem() is then > called in jffs2_build_filesystem() and then again in > jffs2_do_fill_super(). > > Finally we can observe the following report: > ================================================================== > BUG: KASAN: use-after-free in jffs2_clear_xattr_subsystem+0x95/0x6ac > Read of size 8 at addr ffff8881243384e0 by task mount/719 > > Call Trace: > dump_stack+0x115/0x16b > jffs2_clear_xattr_subsystem+0x95/0x6ac > jffs2_do_fill_super+0x84f/0xc30 > jffs2_fill_super+0x2ea/0x4c0 > mtd_get_sb+0x254/0x400 > mtd_get_sb_by_nr+0x4f/0xd0 > get_tree_mtd+0x498/0x840 > jffs2_get_tree+0x25/0x30 > vfs_get_tree+0x8d/0x2e0 > path_mount+0x50f/0x1e50 > do_mount+0x107/0x130 > __se_sys_mount+0x1c5/0x2f0 > __x64_sys_mount+0xc7/0x160 > do_syscall_64+0x45/0x70 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Allocated by task 719: > kasan_save_stack+0x23/0x60 > __kasan_kmalloc.constprop.0+0x10b/0x120 > kasan_slab_alloc+0x12/0x20 > kmem_cache_alloc+0x1c0/0x870 > jffs2_alloc_xattr_ref+0x2f/0xa0 > jffs2_scan_medium.cold+0x3713/0x4794 > jffs2_do_mount_fs.cold+0xa7/0x2253 > jffs2_do_fill_super+0x383/0xc30 > jffs2_fill_super+0x2ea/0x4c0 > [...] > > Freed by task 719: > kmem_cache_free+0xcc/0x7b0 > jffs2_free_xattr_ref+0x78/0x98 > jffs2_clear_xattr_subsystem+0xa1/0x6ac > jffs2_do_mount_fs.cold+0x5e6/0x2253 > jffs2_do_fill_super+0x383/0xc30 > jffs2_fill_super+0x2ea/0x4c0 > [...] > > The buggy address belongs to the object at ffff8881243384b8 > which belongs to the cache jffs2_xattr_ref of size 48 > The buggy address is located 40 bytes inside of > 48-byte region [ffff8881243384b8, ffff8881243384e8) > [...] > ================================================================== > > The triggering of the BUG is shown in the following stack: > ----------------------------------------------------------- > jffs2_fill_super > jffs2_do_fill_super > jffs2_do_mount_fs > jffs2_build_filesystem > jffs2_scan_medium > jffs2_scan_eraseblock <--- ERROR > jffs2_clear_xattr_subsystem <--- free > jffs2_clear_xattr_subsystem <--- free again > ----------------------------------------------------------- > > An error is returned in jffs2_do_mount_fs(). If the error is returned > by jffs2_sum_init(), the jffs2_clear_xattr_subsystem() does not need to > be executed. If the error is returned by jffs2_build_filesystem(), the > jffs2_clear_xattr_subsystem() also does not need to be executed again. > So move jffs2_clear_xattr_subsystem() from 'out_inohash' to 'out_root' > to fix this UAF problem. > > Fixes: aa98d7cf59b5 ("[JFFS2][XATTR] XATTR support on JFFS2 (version. 5)") > Cc: stable@vger.kernel.org > Reported-by: Hulk Robot <hulkci@huawei.com> > Signed-off-by: Baokun Li <libaokun1@huawei.com> > --- > fs/jffs2/fs.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c > index 2ac410477c4f..71f03a5d36ed 100644 > --- a/fs/jffs2/fs.c > +++ b/fs/jffs2/fs.c > @@ -603,8 +603,8 @@ int jffs2_do_fill_super(struct super_block *sb, struct fs_context *fc) > jffs2_free_ino_caches(c); > jffs2_free_raw_node_refs(c); > kvfree(c->blocks); > - out_inohash: > jffs2_clear_xattr_subsystem(c); > + out_inohash: > kfree(c->inocache_list); > out_wbuf: > jffs2_flash_cleanup(c);
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