kernel/git/stable/linux.git/fs/fuse, branch linux-5.8.y

fuse: fix page dereference after free

2020-11-01T11:45:41+00:00

commit d78092e4937de9ce55edcb4ee4c5e3c707be0190 upstream. After unlock_request() pages from the ap->pages[] array may be put (e.g. by aborting the connection) and the pages can be freed. Prevent use after free by grabbing a reference to the page before calling unlock_request(). The original patch was created by Pradeep P V K. Reported-by: Pradeep P V K Cc: Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

fuse: fix the ->direct_IO() treatment of iov_iter

2020-10-07T06:02:48+00:00

[ Upstream commit 933a3752babcf6513117d5773d2b70782d6ad149 ] the callers rely upon having any iov_iter_truncate() done inside ->direct_IO() countered by iov_iter_reexpand(). Reported-by: Qian Cai Tested-by: Qian Cai Signed-off-by: Al Viro Signed-off-by: Sasha Levin

fuse: Fix parameter for FS_IOC_{GET,SET}FLAGS

2020-07-15T12:18:20+00:00

The ioctl encoding for this parameter is a long but the documentation says it should be an int and the kernel drivers expect it to be an int. If the fuse driver treats this as a long it might end up scribbling over the stack of a userspace process that only allocated enough space for an int. This was previously discussed in [1] and a patch for fuse was proposed in [2]. From what I can tell the patch in [2] was nacked in favor of adding new, "fixed" ioctls and using those from userspace. However there is still no "fixed" version of these ioctls and the fact is that it's sometimes infeasible to change all userspace to use the new one. Handling the ioctls specially in the fuse driver seems like the most pragmatic way for fuse servers to support them without causing crashes in userspace applications that call them. [1]: https://lore.kernel.org/linux-fsdevel/20131126200559.GH20559@hall.aurel32.net/T/ [2]: https://sourceforge.net/p/fuse/mailman/message/31771759/ Signed-off-by: Chirantan Ekbote Fixes: 59efec7b9039 ("fuse: implement ioctl support") Cc: Signed-off-by: Miklos Szeredi

fuse: don't ignore errors from fuse_writepages_fill()

2020-07-14T12:45:42+00:00

fuse_writepages() ignores some errors taken from fuse_writepages_fill() I believe it is a bug: if .writepages is called with WB_SYNC_ALL it should either guarantee that all data was successfully saved or return error. Fixes: 26d614df1da9 ("fuse: Implement writepages callback") Signed-off-by: Vasily Averin Signed-off-by: Miklos Szeredi

fuse: clean up condition for writepage sending

2020-07-14T12:45:41+00:00

fuse_writepages_fill uses following construction: if (wpa && ap->num_pages && (A || B || C)) { action; } else if (wpa && D) { if (E) { the same action; } } - ap->num_pages check is always true and can be removed - "if" and "else if" calls the same action and can be merged. Move checking A, B, C, D, E conditions to a helper, add comments. Original-patch-by: Vasily Averin Signed-off-by: Miklos Szeredi

fuse: reject options on reconfigure via fsconfig(2)

2020-07-14T12:45:41+00:00

Previous patch changed handling of remount/reconfigure to ignore all options, including those that are unknown to the fuse kernel fs. This was done for backward compatibility, but this likely only affects the old mount(2) API. The new fsconfig(2) based reconfiguration could possibly be improved. This would make the new API less of a drop in replacement for the old, OTOH this is a good chance to get rid of some weirdnesses in the old API. Several other behaviors might make sense: 1) unknown options are rejected, known options are ignored 2) unknown options are rejected, known options are rejected if the value is changed, allowed otherwise 3) all options are rejected Prior to the backward compatibility fix to ignore all options all known options were accepted (1), even if they change the value of a mount parameter; fuse_reconfigure() does not look at the config values set by fuse_parse_param(). To fix that we'd need to verify that the value provided is the same as set in the initial configuration (2). The major drawback is that this is much more complex than just rejecting all attempts at changing options (3); i.e. all options signify initial configuration values and don't make sense on reconfigure. This patch opts for (3) with the rationale that no mount options are reconfigurable in fuse. Signed-off-by: Miklos Szeredi

fuse: ignore 'data' argument of mount(..., MS_REMOUNT)

2020-07-14T12:45:41+00:00

The command mount -o remount -o unknownoption /mnt/fuse succeeds on kernel versions prior to v5.4 and fails on kernel version at or after. This is because fuse_parse_param() rejects any unrecognised options in case of FS_CONTEXT_FOR_RECONFIGURE, just as for FS_CONTEXT_FOR_MOUNT. This causes a regression in case the fuse filesystem is in fstab, since remount sends all options found there to the kernel; even ones that are meant for the initial mount and are consumed by the userspace fuse server. Fix this by ignoring mount options, just as fuse_remount_fs() did prior to the conversion to the new API. Reported-by: Stefan Priebe Fixes: c30da2e981a7 ("fuse: convert to use the new mount API") Cc: # v5.4 Signed-off-by: Miklos Szeredi

fuse: use ->reconfigure() instead of ->remount_fs()

2020-07-14T12:45:41+00:00

s_op->remount_fs() is only called from legacy_reconfigure(), which is not used after being converted to the new API. Convert to using ->reconfigure(). This restores the previous behavior of syncing the filesystem and rejecting MS_MANDLOCK on remount. Fixes: c30da2e981a7 ("fuse: convert to use the new mount API") Cc: # v5.4 Signed-off-by: Miklos Szeredi

fuse: fix warning in tree_insert() and clean up writepage insertion

2020-07-14T12:45:41+00:00

fuse_writepages_fill() calls tree_insert() with ap->num_pages = 0 which triggers the following warning: WARNING: CPU: 1 PID: 17211 at fs/fuse/file.c:1728 tree_insert+0xab/0xc0 [fuse] RIP: 0010:tree_insert+0xab/0xc0 [fuse] Call Trace: fuse_writepages_fill+0x5da/0x6a0 [fuse] write_cache_pages+0x171/0x470 fuse_writepages+0x8a/0x100 [fuse] do_writepages+0x43/0xe0 Fix up the warning and clean up the code around rb-tree insertion: - Rename tree_insert() to fuse_insert_writeback() and make it return the conflicting entry in case of failure - Re-add tree_insert() as a wrapper around fuse_insert_writeback() - Rename fuse_writepage_in_flight() to fuse_writepage_add() and reverse the meaning of the return value to mean + "true" in case the writepage entry was successfully added + "false" in case it was in-fligt queued on an existing writepage entry's auxiliary list or the existing writepage entry's temporary page updated Switch from fuse_find_writeback() + tree_insert() to fuse_insert_writeback() - Move setting orig_pages to before inserting/updating the entry; this may result in the orig_pages value being discarded later in case of an in-flight request - In case of a new writepage entry use fuse_writepage_add() unconditionally, only set data->wpa if the entry was added. Fixes: 6b2fb79963fb ("fuse: optimize writepages search") Reported-by: kernel test robot Original-path-by: Vasily Averin Signed-off-by: Miklos Szeredi

fuse: move rb_erase() before tree_insert()

2020-07-14T12:45:41+00:00

In fuse_writepage_end() the old writepages entry needs to be removed from the rbtree before inserting the new one, otherwise tree_insert() would fail. This is a very rare codepath and no reproducer exists. Signed-off-by: Miklos Szeredi