The patch below does not apply to the 5.2-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e9eec6a55c95fb918036bfe29c26a535dca1ad49 Mon Sep 17 00:00:00 2001

From: Yishai Hadas yishaih@mellanox.com Date: Thu, 8 Aug 2019 11:15:38 +0300 Subject: [PATCH] IB/mlx5: Fix use-after-free error while accessing ev_file pointer

Call to uverbs_close_fd() releases file pointer to 'ev_file' and mlx5_ib_dev is going to be inaccessible. Cache pointer prior cleaning resources to solve the KASAN warning below.

BUG: KASAN: use-after-free in devx_async_event_close+0x391/0x480 [mlx5_ib] Read of size 8 at addr ffff888301e3cec0 by task devx_direct_tes/4631 CPU: 1 PID: 4631 Comm: devx_direct_tes Tainted: G OE 5.3.0-rc1-for-upstream-dbg-2019-07-26_01-19-56-93 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu2 04/01/2014 Call Trace: dump_stack+0x9a/0xeb print_address_description+0x1e2/0x400 ? devx_async_event_close+0x391/0x480 [mlx5_ib] __kasan_report+0x15c/0x1df ? devx_async_event_close+0x391/0x480 [mlx5_ib] kasan_report+0xe/0x20 devx_async_event_close+0x391/0x480 [mlx5_ib] __fput+0x26a/0x7b0 task_work_run+0x10d/0x180 exit_to_usermode_loop+0x137/0x160 do_syscall_64+0x3c7/0x490 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f5df907d664 Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 80 00 00 00 00 8b 05 6a cd 20 00 48 63 ff 85 c0 75 13 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 44 f3 c3 66 90 48 83 ec 18 48 89 7c 24 08 e8 RSP: 002b:00007ffd353cb958 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 000056017a88c348 RCX: 00007f5df907d664 RDX: 00007f5df969d400 RSI: 00007f5de8f1ec90 RDI: 0000000000000006 RBP: 00007f5df9681dc0 R08: 00007f5de8736410 R09: 000056017a9d2dd0 R10: 000000000000000b R11: 0000000000000246 R12: 00007f5de899d7d0 R13: 00007f5df96c4248 R14: 00007f5de8f1ecb0 R15: 000056017ae41308

Allocated by task 4631: save_stack+0x19/0x80 kasan_kmalloc.constprop.3+0xa0/0xd0 alloc_uobj+0x71/0x230 [ib_uverbs] alloc_begin_fd_uobject+0x2e/0xc0 [ib_uverbs] rdma_alloc_begin_uobject+0x96/0x140 [ib_uverbs] ib_uverbs_run_method+0xdf0/0x1940 [ib_uverbs] ib_uverbs_cmd_verbs+0x57e/0xdb0 [ib_uverbs] ib_uverbs_ioctl+0x177/0x260 [ib_uverbs] do_vfs_ioctl+0x18f/0x1010 ksys_ioctl+0x70/0x80 __x64_sys_ioctl+0x6f/0xb0 do_syscall_64+0x95/0x490 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 4631: save_stack+0x19/0x80 __kasan_slab_free+0x11d/0x160 slab_free_freelist_hook+0x67/0x1a0 kfree+0xb9/0x2a0 uverbs_close_fd+0x118/0x1c0 [ib_uverbs] devx_async_event_close+0x28a/0x480 [mlx5_ib] __fput+0x26a/0x7b0 task_work_run+0x10d/0x180 exit_to_usermode_loop+0x137/0x160 do_syscall_64+0x3c7/0x490 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888301e3cda8 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 280 bytes inside of 512-byte region [ffff888301e3cda8, ffff888301e3cfa8) The buggy address belongs to the page: page:ffffea000c078e00 refcount:1 mapcount:0 mapping:ffff888352811300 index:0x0 compound_mapcount: 0 flags: 0x2fffff80010200(slab|head) raw: 002fffff80010200 ffffea000d152608 ffffea000c077808 ffff888352811300 raw: 0000000000000000 0000000000250025 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888301e3cd80: fc fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb ffff888301e3ce00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888301e3ce80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888301e3cf00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888301e3cf80: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc Disabling lock debugging due to kernel taint

Cc: stable@vger.kernel.org # 5.2 Fixes: 759738537142 ("IB/mlx5: Enable subscription for device events over DEVX") Signed-off-by: Yishai Hadas yishaih@mellanox.com Signed-off-by: Leon Romanovsky leonro@mellanox.com Reviewed-by: Jason Gunthorpe jgg@mellanox.com Link: https://lore.kernel.org/r/20190808081538.28772-1-leon@kernel.org Signed-off-by: Doug Ledford dledford@redhat.com

diff --git a/drivers/infiniband/hw/mlx5/devx.c b/drivers/infiniband/hw/mlx5/devx.c index 2d1b3d9609d9..af5bbb35c058 100644 --- a/drivers/infiniband/hw/mlx5/devx.c +++ b/drivers/infiniband/hw/mlx5/devx.c @@ -2644,12 +2644,13 @@ static int devx_async_event_close(struct inode *inode, struct file *filp) struct devx_async_event_file *ev_file = filp->private_data; struct devx_event_subscription *event_sub, *event_sub_tmp; struct devx_async_event_data *entry, *tmp; + struct mlx5_ib_dev *dev = ev_file->dev;

- mutex_lock(&ev_file->dev->devx_event_table.event_xa_lock); + mutex_lock(&dev->devx_event_table.event_xa_lock); /* delete the subscriptions which are related to this FD */ list_for_each_entry_safe(event_sub, event_sub_tmp, &ev_file->subscribed_events_list, file_list) { - devx_cleanup_subscription(ev_file->dev, event_sub); + devx_cleanup_subscription(dev, event_sub); if (event_sub->eventfd) eventfd_ctx_put(event_sub->eventfd);

@@ -2658,7 +2659,7 @@ static int devx_async_event_close(struct inode *inode, struct file *filp) kfree_rcu(event_sub, rcu); }

- mutex_unlock(&ev_file->dev->devx_event_table.event_xa_lock); + mutex_unlock(&dev->devx_event_table.event_xa_lock);

/* free the pending events allocation */ if (!ev_file->omit_data) { @@ -2670,7 +2671,7 @@ static int devx_async_event_close(struct inode *inode, struct file *filp) }

uverbs_close_fd(filp); - put_device(&ev_file->dev->ib_dev.dev); + put_device(&dev->ib_dev.dev); return 0; }