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[ Upstream commit4121fb0db6] In disassociate flow, the type_attrs is set to be NULL, which is in an implicit way is checked in alloc_uobj() by "if (!attrs->context)". Change the logic to rely on that check, to be consistent with other alloc_uobj() places that will fix the following kernel splat. BUG: kernel NULL pointer dereference, address: 0000000000000018 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 3 PID: 2743 Comm: python3 Not tainted 5.7.0-rc6-for-upstream-perf-2020-05-23_19-04-38-5 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 RIP: 0010:alloc_begin_fd_uobject+0x18/0xf0 [ib_uverbs] Code: 89 43 48 eb 97 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 41 55 49 89 f5 41 54 55 48 89 fd 53 48 83 ec 08 48 8b 1f <48> 8b 43 18 48 8b 80 80 00 00 00 48 3d 20 10 33 a0 74 1c 48 3d 30 RSP: 0018:ffffc90001127b70 EFLAGS: 00010282 RAX: ffffffffa0339fe0 RBX: 0000000000000000 RCX: 8000000000000007 RDX: fffffffffffffffb RSI: ffffc90001127d28 RDI: ffff88843fe1f600 RBP: ffff88843fe1f600 R08: ffff888461eb06d8 R09: ffff888461eb06f8 R10: ffff888461eb0700 R11: 0000000000000000 R12: ffff88846a5f6450 R13: ffffc90001127d28 R14: ffff88845d7d6ea0 R15: ffffc90001127cb8 FS: 00007f469bff1540(0000) GS:ffff88846f980000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000018 CR3: 0000000450018003 CR4: 0000000000760ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: ? xa_store+0x28/0x40 rdma_alloc_begin_uobject+0x4f/0x90 [ib_uverbs] ib_uverbs_create_comp_channel+0x87/0xf0 [ib_uverbs] ib_uverbs_handler_UVERBS_METHOD_INVOKE_WRITE+0xb1/0xf0 [ib_uverbs] ib_uverbs_cmd_verbs.isra.8+0x96d/0xae0 [ib_uverbs] ? get_page_from_freelist+0x3bb/0xf70 ? _copy_to_user+0x22/0x30 ? uverbs_disassociate_api+0xd0/0xd0 [ib_uverbs] ? __wake_up_common_lock+0x87/0xc0 ib_uverbs_ioctl+0xbc/0x130 [ib_uverbs] ksys_ioctl+0x83/0xc0 ? ksys_write+0x55/0xd0 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x48/0x130 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f469ac43267 Fixes:849e149063("RDMA/core: Do not allow alloc_commit to fail") Link: https://lore.kernel.org/r/20200617061826.2625359-1-leon@kernel.org Signed-off-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.