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David Howells dd01312a5f afs: Fix NULL deref in afs_dynroot_depopulate()
[ Upstream commit 5e0b17b026eb7c6de9baa9b0d45a51b05f05abe1 ]

If an error occurs during the construction of an afs superblock, it's
possible that an error occurs after a superblock is created, but before
we've created the root dentry.  If the superblock has a dynamic root
(ie.  what's normally mounted on /afs), the afs_kill_super() will call
afs_dynroot_depopulate() to unpin any created dentries - but this will
oops if the root hasn't been created yet.

Fix this by skipping that bit of code if there is no root dentry.

This leads to an oops looking like:

	general protection fault, ...
	KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
	...
	RIP: 0010:afs_dynroot_depopulate+0x25f/0x529 fs/afs/dynroot.c:385
	...
	Call Trace:
	 afs_kill_super+0x13b/0x180 fs/afs/super.c:535
	 deactivate_locked_super+0x94/0x160 fs/super.c:335
	 afs_get_tree+0x1124/0x1460 fs/afs/super.c:598
	 vfs_get_tree+0x89/0x2f0 fs/super.c:1547
	 do_new_mount fs/namespace.c:2875 [inline]
	 path_mount+0x1387/0x2070 fs/namespace.c:3192
	 do_mount fs/namespace.c:3205 [inline]
	 __do_sys_mount fs/namespace.c:3413 [inline]
	 __se_sys_mount fs/namespace.c:3390 [inline]
	 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3390
	 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

which is oopsing on this line:

	inode_lock(root->d_inode);

presumably because sb->s_root was NULL.

Fixes: 0da0b7fd73e4 ("afs: Display manually added cells in dynamic root mount")
Reported-by: syzbot+c1eff8205244ae7e11a6@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-03-16 16:34:40 +08:00
Documentation kbuild: support LLVM=1 to switch the default tools to Clang/LLVM 2021-03-16 16:34:25 +08:00
LICENSES Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
arch Fix build error when CONFIG_ACPI is not set/enabled: 2021-03-16 16:34:40 +08:00
block iocost: Fix check condition of iocg abs_vdebt 2021-03-16 16:33:18 +08:00
certs Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
crypto crypto: algif_aead - fix uninitialized ctx->init 2021-03-16 16:34:22 +08:00
drivers RDMA/bnxt_re: Do not add user qps to flushlist 2021-03-16 16:34:40 +08:00
fs afs: Fix NULL deref in afs_dynroot_depopulate() 2021-03-16 16:34:40 +08:00
include iommu/vt-d: Enforce PASID devTLB field mask 2021-03-16 16:34:16 +08:00
init x86: Fix early boot crash on gcc-10, third try 2021-03-16 16:28:02 +08:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2021-03-16 16:27:51 +08:00
kernel kthread: Do not preempt current task if it is going to call schedule() 2021-03-16 16:34:30 +08:00
lib test_kmod: avoid potential double free in trigger_config_run_type() 2021-03-16 16:34:21 +08:00
mm mm, page_alloc: fix core hung in free_pcppages_bulk() 2021-03-16 16:34:29 +08:00
net can: j1939: add rxtimer for multipacket broadcast session 2021-03-16 16:34:37 +08:00
package config/arm64: OPEN CONFIG_PSI and phytium configs 2021-03-16 11:02:59 +08:00
samples bpf: Fix fds_example SIGSEGV error 2021-03-16 16:33:24 +08:00
scripts kconfig: qconf: fix signal connection to invalid slots 2021-03-16 16:34:39 +08:00
security Smack: prevent underflow in smk_set_cipso() 2021-03-16 16:33:40 +08:00
sound ASoC: intel: Fix memleak in sst_media_open 2021-03-16 16:34:38 +08:00
tools tools/testing/selftests/cgroup/cgroup_util.c: cg_read_strcmp: fix null pointer dereference 2021-03-16 16:34:34 +08:00
usr Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
virt KVM: arm64: Don't inherit exec permission across page-table levels 2021-03-16 16:32:57 +08:00
.clang-format Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
.cocciconfig Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
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CREDITS Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
Kbuild Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
Kconfig Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2021-03-16 16:34:24 +08:00
Makefile kbuild: support LLVM=1 to switch the default tools to Clang/LLVM 2021-03-16 16:34:25 +08:00
README Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
README.md Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
backport_remove_lists.txt Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
tools_key.pub Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00

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Tencent Linux Kernel 4.0