From: Rohith Surabattula Date: Thu, 20 May 2021 16:45:01 +0000 (+0000) Subject: Fix KASAN identified use-after-free issue. X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=9687c85dfbf84a6a37522626b4d5c5191a695e6c;p=linux.git Fix KASAN identified use-after-free issue. [ 612.157429] ================================================================== [ 612.158275] BUG: KASAN: use-after-free in process_one_work+0x90/0x9b0 [ 612.158801] Read of size 8 at addr ffff88810a31ca60 by task kworker/2:9/2382 [ 612.159611] CPU: 2 PID: 2382 Comm: kworker/2:9 Tainted: G OE 5.13.0-rc2+ #98 [ 612.159623] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014 [ 612.159640] Workqueue: 0x0 (deferredclose) [ 612.159669] Call Trace: [ 612.159685] dump_stack+0xbb/0x107 [ 612.159711] print_address_description.constprop.0+0x18/0x140 [ 612.159733] ? process_one_work+0x90/0x9b0 [ 612.159743] ? process_one_work+0x90/0x9b0 [ 612.159754] kasan_report.cold+0x7c/0xd8 [ 612.159778] ? lock_is_held_type+0x80/0x130 [ 612.159789] ? process_one_work+0x90/0x9b0 [ 612.159812] kasan_check_range+0x145/0x1a0 [ 612.159834] process_one_work+0x90/0x9b0 [ 612.159877] ? pwq_dec_nr_in_flight+0x110/0x110 [ 612.159914] ? spin_bug+0x90/0x90 [ 612.159967] worker_thread+0x3b6/0x6c0 [ 612.160023] ? process_one_work+0x9b0/0x9b0 [ 612.160038] kthread+0x1dc/0x200 [ 612.160051] ? kthread_create_worker_on_cpu+0xd0/0xd0 [ 612.160092] ret_from_fork+0x1f/0x30 [ 612.160399] Allocated by task 2358: [ 612.160757] kasan_save_stack+0x1b/0x40 [ 612.160768] __kasan_kmalloc+0x9b/0xd0 [ 612.160778] cifs_new_fileinfo+0xb0/0x960 [cifs] [ 612.161170] cifs_open+0xadf/0xf20 [cifs] [ 612.161421] do_dentry_open+0x2aa/0x6b0 [ 612.161432] path_openat+0xbd9/0xfa0 [ 612.161441] do_filp_open+0x11d/0x230 [ 612.161450] do_sys_openat2+0x115/0x240 [ 612.161460] __x64_sys_openat+0xce/0x140 When mod_delayed_work is called to modify the delay of pending work, it might return false and queue a new work when pending work is already scheduled or when try to grab pending work failed. So, Increase the reference count when new work is scheduled to avoid use-after-free. Signed-off-by: Rohith Surabattula Signed-off-by: Steve French --- diff --git a/fs/cifs/file.c b/fs/cifs/file.c index a1abd3da1d442..379a427f3c2f1 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -874,10 +874,6 @@ void smb2_deferred_work_close(struct work_struct *work) struct cifsFileInfo, deferred.work); spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock); - if (!cfile->deferred_close_scheduled) { - spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock); - return; - } cifs_del_deferred_close(cfile); cfile->deferred_close_scheduled = false; spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock); @@ -904,8 +900,13 @@ int cifs_close(struct inode *inode, struct file *file) cifs_add_deferred_close(cfile, dclose); if (cfile->deferred_close_scheduled && delayed_work_pending(&cfile->deferred)) { - mod_delayed_work(deferredclose_wq, - &cfile->deferred, cifs_sb->ctx->acregmax); + /* + * If there is no pending work, mod_delayed_work queues new work. + * So, Increase the ref count to avoid use-after-free. + */ + if (!mod_delayed_work(deferredclose_wq, + &cfile->deferred, cifs_sb->ctx->acregmax)) + cifsFileInfo_get(cfile); } else { /* Deferred close for files */ queue_delayed_work(deferredclose_wq, @@ -4879,7 +4880,12 @@ oplock_break_ack: if (is_deferred && cfile->deferred_close_scheduled && delayed_work_pending(&cfile->deferred)) { - mod_delayed_work(deferredclose_wq, &cfile->deferred, 0); + /* + * If there is no pending work, mod_delayed_work queues new work. + * So, Increase the ref count to avoid use-after-free. + */ + if (!mod_delayed_work(deferredclose_wq, &cfile->deferred, 0)) + cifsFileInfo_get(cfile); } spin_unlock(&CIFS_I(inode)->deferred_lock); _cifsFileInfo_put(cfile, false /* do not wait for ourself */, false); diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c index 34f2a7e80c581..7207a63819cbf 100644 --- a/fs/cifs/misc.c +++ b/fs/cifs/misc.c @@ -674,6 +674,8 @@ cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink, /* * Critical section which runs after acquiring deferred_lock. + * As there is no reference count on cifs_deferred_close, pdclose + * should not be used outside deferred_lock. */ bool cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose) @@ -752,8 +754,14 @@ cifs_close_all_deferred_files(struct cifs_tcon *tcon) spin_lock(&tcon->open_file_lock); list_for_each(tmp, &tcon->openFileList) { cfile = list_entry(tmp, struct cifsFileInfo, tlist); - if (delayed_work_pending(&cfile->deferred)) - mod_delayed_work(deferredclose_wq, &cfile->deferred, 0); + if (delayed_work_pending(&cfile->deferred)) { + /* + * If there is no pending work, mod_delayed_work queues new work. + * So, Increase the ref count to avoid use-after-free. + */ + if (!mod_delayed_work(deferredclose_wq, &cfile->deferred, 0)) + cifsFileInfo_get(cfile); + } } spin_unlock(&tcon->open_file_lock); }