Nice find, I just came across a deadlock wrt GC and rmdir, hopefully this is he fix.
This needs to go to stable too, sooner rather than later. Jocke On Fri, 2020-06-19 at 17:06 +0800, Zhe Li wrote: > > The log of UAF problem is listed below. > BUG: KASAN: use-after-free in jffs2_rmdir+0xa4/0x1cc [jffs2] at addr c1f165fc > Read of size 4 by task rm/8283 > ============================================================================= > BUG kmalloc-32 (Tainted: P B O ): kasan: bad access detected > ----------------------------------------------------------------------------- > > INFO: Allocated in 0xbbbbbbbb age=3054364 cpu=0 pid=0 > 0xb0bba6ef > jffs2_write_dirent+0x11c/0x9c8 [jffs2] > __slab_alloc.isra.21.constprop.25+0x2c/0x44 > __kmalloc+0x1dc/0x370 > jffs2_write_dirent+0x11c/0x9c8 [jffs2] > jffs2_do_unlink+0x328/0x5fc [jffs2] > jffs2_rmdir+0x110/0x1cc [jffs2] > vfs_rmdir+0x180/0x268 > do_rmdir+0x2cc/0x300 > ret_from_syscall+0x0/0x3c > INFO: Freed in 0x205b age=3054364 cpu=0 pid=0 > 0x2e9173 > jffs2_add_fd_to_list+0x138/0x1dc [jffs2] > jffs2_add_fd_to_list+0x138/0x1dc [jffs2] > jffs2_garbage_collect_dirent.isra.3+0x21c/0x288 [jffs2] > jffs2_garbage_collect_live+0x16bc/0x1800 [jffs2] > jffs2_garbage_collect_pass+0x678/0x11d4 [jffs2] > jffs2_garbage_collect_thread+0x1e8/0x3b0 [jffs2] > kthread+0x1a8/0x1b0 > ret_from_kernel_thread+0x5c/0x64 > Call Trace: > [c17ddd20] [c02452d4] kasan_report.part.0+0x298/0x72c (unreliable) > [c17ddda0] [d2509680] jffs2_rmdir+0xa4/0x1cc [jffs2] > [c17dddd0] [c026da04] vfs_rmdir+0x180/0x268 > [c17dde00] [c026f4e4] do_rmdir+0x2cc/0x300 > [c17ddf40] [c001a658] ret_from_syscall+0x0/0x3c > > The root cause is that we don't get "jffs2_inode_info.sem" before > we scan list "jffs2_inode_info.dents" in function jffs2_rmdir. > This patch add codes to get "jffs2_inode_info.sem" before we scan > "jffs2_inode_info.dents" to slove the UAF problem. > > Signed-off-by: Zhe Li <[email protected]> > --- > fs/jffs2/dir.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/fs/jffs2/dir.c b/fs/jffs2/dir.c > index f20cff1..7764937 100644 > --- a/fs/jffs2/dir.c > +++ b/fs/jffs2/dir.c > @@ -590,10 +590,14 @@ static int jffs2_rmdir (struct inode *dir_i, struct > dentry *dentry) > int ret; > uint32_t now = JFFS2_NOW(); > > + mutex_lock(&f->sem); > for (fd = f->dents ; fd; fd = fd->next) { > - if (fd->ino) > + if (fd->ino) { > + mutex_unlock(&f->sem); > return -ENOTEMPTY; > + } > } > + mutex_unlock(&f->sem); > > ret = jffs2_do_unlink(c, dir_f, dentry->d_name.name, > dentry->d_name.len, f, now); > -- > 2.7.4 > > > > ______________________________________________________ > Linux MTD discussion mailing list > https://nam03.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.infradead.org%2Fmailman%2Flistinfo%2Flinux-mtd%2F&data=02%7C01%7Cjoakim.tjernlund%40infinera.com%7C339a1184745b4c76bdf908d8143043b2%7C285643de5f5b4b03a1530ae2dc8aaf77%7C1%7C1%7C637281544815697582&sdata=jKo97fc3j6jVcjVpS2exm0sDL%2BWr6DqkTe6jqe8G9t8%3D&reserved=0
