kernel/linux.git/fs/autofs, branch v5.15.208

autofs: fix memory leak of waitqueues in autofs_catatonic_mode

2023-09-23T09:09:54+00:00

[ Upstream commit ccbe77f7e45dfb4420f7f531b650c00c6e9c7507 ] Syzkaller reports a memory leak: BUG: memory leak unreferenced object 0xffff88810b279e00 (size 96): comm "syz-executor399", pid 3631, jiffies 4294964921 (age 23.870s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 08 9e 27 0b 81 88 ff ff ..........'..... 08 9e 27 0b 81 88 ff ff 00 00 00 00 00 00 00 00 ..'............. backtrace: [] kmalloc_trace+0x20/0x90 mm/slab_common.c:1046 [] kmalloc include/linux/slab.h:576 [inline] [] autofs_wait+0x3fa/0x9a0 fs/autofs/waitq.c:378 [] autofs_do_expire_multi+0xa7/0x3e0 fs/autofs/expire.c:593 [] autofs_expire_multi+0x53/0x80 fs/autofs/expire.c:619 [] autofs_root_ioctl_unlocked+0x322/0x3b0 fs/autofs/root.c:897 [] autofs_root_ioctl+0x25/0x30 fs/autofs/root.c:910 [] vfs_ioctl fs/ioctl.c:51 [inline] [] __do_sys_ioctl fs/ioctl.c:870 [inline] [] __se_sys_ioctl fs/ioctl.c:856 [inline] [] __x64_sys_ioctl+0xfc/0x140 fs/ioctl.c:856 [] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 [] entry_SYSCALL_64_after_hwframe+0x63/0xcd autofs_wait_queue structs should be freed if their wait_ctr becomes zero. Otherwise they will be lost. In this case an AUTOFS_IOC_EXPIRE_MULTI ioctl is done, then a new waitqueue struct is allocated in autofs_wait(), its initial wait_ctr equals 2. After that wait_event_killable() is interrupted (it returns -ERESTARTSYS), so that 'wq->name.name == NULL' condition may be not satisfied. Actually, this condition can be satisfied when autofs_wait_release() or autofs_catatonic_mode() is called and, what is also important, wait_ctr is decremented in those places. Upon the exit of autofs_wait(), wait_ctr is decremented to 1. Then the unmounting process begins: kill_sb calls autofs_catatonic_mode(), which should have freed the waitqueues, but it only decrements its usage counter to zero which is not a correct behaviour. edit:imk This description is of course not correct. The umount performed as a result of an expire is a umount of a mount that has been automounted, it's not the autofs mount itself. They happen independently, usually after everything mounted within the autofs file system has been expired away. If everything hasn't been expired away the automount daemon can still exit leaving mounts in place. But expires done in both cases will result in a notification that calls autofs_wait_release() with a result status. The problem case is the summary execution of of the automount daemon. In this case any waiting processes won't be woken up until either they are terminated or the mount is umounted. end edit: imk So in catatonic mode we should free waitqueues which counter becomes zero. edit: imk Initially I was concerned that the calling of autofs_wait_release() and autofs_catatonic_mode() was not mutually exclusive but that can't be the case (obviously) because the queue entry (or entries) is removed from the list when either of these two functions are called. Consequently the wait entry will be freed by only one of these functions or by the woken process in autofs_wait() depending on the order of the calls. end edit: imk Reported-by: syzbot+5e53f70e69ff0c0a1c0c@syzkaller.appspotmail.com Suggested-by: Takeshi Misawa Signed-off-by: Fedor Pchelkin Signed-off-by: Alexey Khoroshilov Signed-off-by: Ian Kent Cc: Matthew Wilcox Cc: Andrei Vagin Cc: autofs@vger.kernel.org Cc: linux-kernel@vger.kernel.org Message-Id: <169112719161.7590.6700123246297365841.stgit@donald.themaw.net> Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

autofs: fix wait name hash calculation in autofs_wait()

2021-10-21T01:09:02+00:00

There's a mistake in commit 2be7828c9fefc ("get rid of autofs_getpath()") that affects kernels from v5.13.0, basically missed because of me not fully testing the change for Al. The problem is that the hash calculation for the wait name qstr hasn't been updated to account for the change to use dentry_path_raw(). This prevents the correct matching an existing wait resulting in multiple notifications being sent to the daemon for the same mount which must not occur. The problem wasn't discovered earlier because it only occurs when multiple processes trigger a request for the same mount concurrently so it only shows up in more aggressive testing. Fixes: 2be7828c9fefc ("get rid of autofs_getpath()") Cc: stable@vger.kernel.org Signed-off-by: Ian Kent Signed-off-by: Al Viro

autofs: should_expire() argument is guaranteed to be positive

2021-03-24T18:14:27+00:00

Signed-off-by: Al Viro

get rid of autofs_getpath()

2021-03-21T15:44:02+00:00

allow wq->name.name to point not at the beginning of the object containing the string, with wq->offset telling how far into it we are. Then we can bloody well just use dentry_path_raw() instead of autofs_getpath() - the only real difference is that dentry_path_raw() puts the result into the end of buffer and returns where it starts. Signed-off-by: Al Viro

fs: make helpers idmap mount aware

2021-01-24T13:27:20+00:00

Extend some inode methods with an additional user namespace argument. A filesystem that is aware of idmapped mounts will receive the user namespace the mount has been marked with. This can be used for additional permission checking and also to enable filesystems to translate between uids and gids if they need to. We have implemented all relevant helpers in earlier patches. As requested we simply extend the exisiting inode method instead of introducing new ones. This is a little more code churn but it's mostly mechanical and doesnt't leave us with additional inode methods. Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com Cc: Christoph Hellwig Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner

file: Replace ksys_close with close_fd

2020-12-10T18:42:59+00:00

Now that ksys_close is exactly identical to close_fd replace the one caller of ksys_close with close_fd. [1] https://lkml.kernel.org/r/20200818112020.GA17080@infradead.org Suggested-by: Christoph Hellwig Link: https://lkml.kernel.org/r/20201120231441.29911-22-ebiederm@xmission.com Signed-off-by: Eric W. Biederman

autofs: harden ioctl table

2020-10-16T18:11:22+00:00

The table of ioctl functions should be marked const in order to put them in read-only memory, and we should use array_index_nospec() to avoid speculation disclosing the contents of kernel memory to userspace. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Acked-by: Ian Kent Link: https://lkml.kernel.org/r/20200818122203.GO17456@casper.infradead.org Signed-off-by: Linus Torvalds

autofs: use __kernel_write() for the autofs pipe writing

2020-09-30T00:18:34+00:00

autofs got broken in some configurations by commit 13c164b1a186 ("autofs: switch to kernel_write") because there is now an extra LSM permission check done by security_file_permission() in rw_verify_area(). autofs is one if the few places that really does want the much more limited __kernel_write(), because the write is an internal kernel one that shouldn't do any user permission checks (it also doesn't need the file_start_write/file_end_write logic, since it's just a pipe). There are a couple of other cases like that - accounting, core dumping, and splice - but autofs stands out because it can be built as a module. As a result, we need to export this internal __kernel_write() function again. We really don't want any other module to use this, but we don't have a "EXPORT_SYMBOL_FOR_AUTOFS_ONLY()". But we can mark it GPL-only to at least approximate that "internal use only" for licensing. While in this area, make autofs pass in NULL for the file position pointer, since it's always a pipe, and we now use a NULL file pointer for streaming file descriptors (see file_ppos() and commit 438ab720c675: "vfs: pass ppos=NULL to .read()/.write() of FMODE_STREAM files") This effectively reverts commits 9db977522449 ("fs: unexport __kernel_write") and 13c164b1a186 ("autofs: switch to kernel_write"). Fixes: 13c164b1a186 ("autofs: switch to kernel_write") Reported-by: Ondrej Mosnacek Acked-by: Christoph Hellwig Acked-by: Acked-by: Ian Kent Signed-off-by: Linus Torvalds

fs: autofs: delete repeated words in comments

2020-08-15T02:56:56+00:00

Drop duplicated words {the, at} in comments. Signed-off-by: Randy Dunlap Signed-off-by: Andrew Morton Acked-by: Ian Kent Link: http://lkml.kernel.org/r/20200811021817.24982-1-rdunlap@infradead.org Signed-off-by: Linus Torvalds

autofs: switch to kernel_write

2020-07-08T06:27:56+00:00

While pipes don't really need sb_writers projection, __kernel_write is an interface better kept private, and the additional rw_verify_area does not hurt here. Signed-off-by: Christoph Hellwig Acked-by: Ian Kent