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Linux kernel source tree
7e86600606
inode->i_private is assigned by a Node pointer only after registering a
new binary format, so it could be NULL if inode was created by
bm_fill_super() (or iput() was called by the error path in
bm_register_write()), and this could result in NULL pointer dereference
when evicting such an inode. e.g. mount binfmt_misc filesystem then
umount it immediately:
mount -t binfmt_misc binfmt_misc /proc/sys/fs/binfmt_misc
umount /proc/sys/fs/binfmt_misc
will result in
BUG: unable to handle kernel NULL pointer dereference at 0000000000000013
IP: bm_evict_inode+0x16/0x40 [binfmt_misc]
...
Call Trace:
evict+0xd3/0x1a0
iput+0x17d/0x1d0
dentry_unlink_inode+0xb9/0xf0
__dentry_kill+0xc7/0x170
shrink_dentry_list+0x122/0x280
shrink_dcache_parent+0x39/0x90
do_one_tree+0x12/0x40
shrink_dcache_for_umount+0x2d/0x90
generic_shutdown_super+0x1f/0x120
kill_litter_super+0x29/0x40
deactivate_locked_super+0x43/0x70
deactivate_super+0x45/0x60
cleanup_mnt+0x3f/0x70
__cleanup_mnt+0x12/0x20
task_work_run+0x86/0xa0
exit_to_usermode_loop+0x6d/0x99
syscall_return_slowpath+0xba/0xf0
entry_SYSCALL_64_fastpath+0xa3/0xa
Fix it by making sure Node (e) is not NULL.
Link: http://lkml.kernel.org/r/20171010100642.31786-1-eguan@redhat.com
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.