From 11c10956515b8ec44cf4f2a7b9d8bf8b9dc05ec4 Mon Sep 17 00:00:00 2001 From: Zhengchao Shao Date: Thu, 10 Nov 2022 20:26:06 +0800 Subject: 9p/fd: fix issue of list_del corruption in p9_fd_cancel() Syz reported the following issue: kernel BUG at lib/list_debug.c:53! invalid opcode: 0000 [#1] PREEMPT SMP KASAN RIP: 0010:__list_del_entry_valid.cold+0x5c/0x72 Call Trace: p9_fd_cancel+0xb1/0x270 p9_client_rpc+0x8ea/0xba0 p9_client_create+0x9c0/0xed0 v9fs_session_init+0x1e0/0x1620 v9fs_mount+0xba/0xb80 legacy_get_tree+0x103/0x200 vfs_get_tree+0x89/0x2d0 path_mount+0x4c0/0x1ac0 __x64_sys_mount+0x33b/0x430 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 The process is as follows: Thread A: Thread B: p9_poll_workfn() p9_client_create() ... ... p9_conn_cancel() p9_fd_cancel() list_del() ... ... list_del() //list_del corruption There is no lock protection when deleting list in p9_conn_cancel(). After deleting list in Thread A, thread B will delete the same list again. It will cause issue of list_del corruption. Setting req->status to REQ_STATUS_ERROR under lock prevents other cleanup paths from trying to manipulate req_list. The other thread can safely check req->status because it still holds a reference to req at this point. Link: https://lkml.kernel.org/r/20221110122606.383352-1-shaozhengchao@huawei.com Fixes: 52f1c45dde91 ("9p: trans_fd/p9_conn_cancel: drop client lock earlier") Reported-by: syzbot+9b69b8d10ab4a7d88056@syzkaller.appspotmail.com Signed-off-by: Zhengchao Shao [Dominique: add description of the fix in commit message] Signed-off-by: Dominique Martinet --- net/9p/trans_fd.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'net') diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index 56a186768750..bd28e63d7666 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -202,9 +202,11 @@ static void p9_conn_cancel(struct p9_conn *m, int err) list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) { list_move(&req->req_list, &cancel_list); + req->status = REQ_STATUS_ERROR; } list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) { list_move(&req->req_list, &cancel_list); + req->status = REQ_STATUS_ERROR; } spin_unlock(&m->req_lock); -- cgit From 578b565b240afdfe0596d183f473f333eb9d3008 Mon Sep 17 00:00:00 2001 From: GUO Zihua Date: Thu, 17 Nov 2022 17:11:57 +0800 Subject: 9p/fd: Fix write overflow in p9_read_work This error was reported while fuzzing: BUG: KASAN: slab-out-of-bounds in _copy_to_iter+0xd35/0x1190 Write of size 4043 at addr ffff888008724eb1 by task kworker/1:1/24 CPU: 1 PID: 24 Comm: kworker/1:1 Not tainted 6.1.0-rc5-00002-g1adf73218daa-dirty #223 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014 Workqueue: events p9_read_work Call Trace: dump_stack_lvl+0x4c/0x64 print_report+0x178/0x4b0 kasan_report+0xae/0x130 kasan_check_range+0x179/0x1e0 memcpy+0x38/0x60 _copy_to_iter+0xd35/0x1190 copy_page_to_iter+0x1d5/0xb00 pipe_read+0x3a1/0xd90 __kernel_read+0x2a5/0x760 kernel_read+0x47/0x60 p9_read_work+0x463/0x780 process_one_work+0x91d/0x1300 worker_thread+0x8c/0x1210 kthread+0x280/0x330 ret_from_fork+0x22/0x30 Allocated by task 457: kasan_save_stack+0x1c/0x40 kasan_set_track+0x21/0x30 __kasan_kmalloc+0x7e/0x90 __kmalloc+0x59/0x140 p9_fcall_init.isra.11+0x5d/0x1c0 p9_tag_alloc+0x251/0x550 p9_client_prepare_req+0x162/0x350 p9_client_rpc+0x18d/0xa90 p9_client_create+0x670/0x14e0 v9fs_session_init+0x1fd/0x14f0 v9fs_mount+0xd7/0xaf0 legacy_get_tree+0xf3/0x1f0 vfs_get_tree+0x86/0x2c0 path_mount+0x885/0x1940 do_mount+0xec/0x100 __x64_sys_mount+0x1a0/0x1e0 do_syscall_64+0x3a/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd This BUG pops up when trying to reproduce https://syzkaller.appspot.com/bug?id=6c7cd46c7bdd0e86f95d26ec3153208ad186f9fa The callstack is different but the issue is valid and re-producable with the same re-producer in the link. The root cause of this issue is that we check the size of the message received against the msize of the client in p9_read_work. However, it turns out that capacity is no longer consistent with msize. Thus, the message size should be checked against sdata capacity. As the msize is non-consistant with the capacity of the tag and as we are now checking message size against capacity directly, there is no point checking message size against msize. So remove it. Link: https://lkml.kernel.org/r/20221117091159.31533-2-guozihua@huawei.com Link: https://lkml.kernel.org/r/20221117091159.31533-3-guozihua@huawei.com Reported-by: syzbot+0f89bd13eaceccc0e126@syzkaller.appspotmail.com Fixes: 60ece0833b6c ("net/9p: allocate appropriate reduced message buffers") Signed-off-by: GUO Zihua Reviewed-by: Christian Schoenebeck [Dominique: squash patches 1 & 2 and fix size including header part] Signed-off-by: Dominique Martinet --- net/9p/trans_fd.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'net') diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index bd28e63d7666..27c5c938ccd1 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -324,14 +324,6 @@ static void p9_read_work(struct work_struct *work) goto error; } - if (m->rc.size >= m->client->msize) { - p9_debug(P9_DEBUG_ERROR, - "requested packet size too big: %d\n", - m->rc.size); - err = -EIO; - goto error; - } - p9_debug(P9_DEBUG_TRANS, "mux %p pkt: size: %d bytes tag: %d\n", m, m->rc.size, m->rc.tag); @@ -344,6 +336,14 @@ static void p9_read_work(struct work_struct *work) goto error; } + if (m->rc.size > m->rreq->rc.capacity) { + p9_debug(P9_DEBUG_ERROR, + "requested packet size too big: %d for tag %d with capacity %zd\n", + m->rc.size, m->rc.tag, m->rreq->rc.capacity); + err = -EIO; + goto error; + } + if (!m->rreq->rc.sdata) { p9_debug(P9_DEBUG_ERROR, "No recv fcall for tag %d (req %p), disconnecting!\n", -- cgit From 6854fadbeee10891ed74246bdc05031906b6c8cf Mon Sep 17 00:00:00 2001 From: GUO Zihua Date: Thu, 17 Nov 2022 17:11:59 +0800 Subject: 9p/fd: Use P9_HDRSZ for header size Cleanup hardcoded header sizes to use P9_HDRSZ instead of '7' Link: https://lkml.kernel.org/r/20221117091159.31533-4-guozihua@huawei.com Signed-off-by: GUO Zihua Reviewed-by: Christian Schoenebeck [Dominique: commit message adjusted to make sense after offset size adjustment got removed] Signed-off-by: Dominique Martinet --- net/9p/trans_fd.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'net') diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index 27c5c938ccd1..eeea0a6a75b6 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -120,7 +120,7 @@ struct p9_conn { struct list_head unsent_req_list; struct p9_req_t *rreq; struct p9_req_t *wreq; - char tmp_buf[7]; + char tmp_buf[P9_HDRSZ]; struct p9_fcall rc; int wpos; int wsize; @@ -293,7 +293,7 @@ static void p9_read_work(struct work_struct *work) if (!m->rc.sdata) { m->rc.sdata = m->tmp_buf; m->rc.offset = 0; - m->rc.capacity = 7; /* start by reading header */ + m->rc.capacity = P9_HDRSZ; /* start by reading header */ } clear_bit(Rpending, &m->wsched); @@ -316,7 +316,7 @@ static void p9_read_work(struct work_struct *work) p9_debug(P9_DEBUG_TRANS, "got new header\n"); /* Header size */ - m->rc.size = 7; + m->rc.size = P9_HDRSZ; err = p9_parse_header(&m->rc, &m->rc.size, NULL, NULL, 0); if (err) { p9_debug(P9_DEBUG_ERROR, -- cgit From 391c18cf776eb4569ecda1f7794f360fe0a45a26 Mon Sep 17 00:00:00 2001 From: Dominique Martinet Date: Fri, 18 Nov 2022 22:44:41 +0900 Subject: 9p/xen: check logical size for buffer size trans_xen did not check the data fits into the buffer before copying from the xen ring, but we probably should. Add a check that just skips the request and return an error to userspace if it did not fit Tested-by: Stefano Stabellini Reviewed-by: Christian Schoenebeck Link: https://lkml.kernel.org/r/20221118135542.63400-1-asmadeus@codewreck.org Signed-off-by: Dominique Martinet --- net/9p/trans_xen.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'net') diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c index b15c64128c3e..aaa5fd364691 100644 --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -208,6 +208,14 @@ static void p9_xen_response(struct work_struct *work) continue; } + if (h.size > req->rc.capacity) { + dev_warn(&priv->dev->dev, + "requested packet size too big: %d for tag %d with capacity %zd\n", + h.size, h.tag, req->rc.capacity); + req->status = REQ_STATUS_ERROR; + goto recv_error; + } + memcpy(&req->rc, &h, sizeof(h)); req->rc.offset = 0; @@ -217,6 +225,7 @@ static void p9_xen_response(struct work_struct *work) masked_prod, &masked_cons, XEN_9PFS_RING_SIZE(ring)); +recv_error: virt_mb(); cons += h.size; ring->intf->in_cons = cons; -- cgit