fd203d2c67
[ Upstream commit f123dc86388cb669c3d6322702dc441abc35c31e ] syzbot is reporting sleep in atomic context in SysV filesystem [1], for sb_bread() is called with rw_spinlock held. A "write_lock(&pointers_lock) => read_lock(&pointers_lock) deadlock" bug and a "sb_bread() with write_lock(&pointers_lock)" bug were introduced by "Replace BKL for chain locking with sysvfs-private rwlock" in Linux 2.5.12. Then, "[PATCH] err1-40: sysvfs locking fix" in Linux 2.6.8 fixed the former bug by moving pointers_lock lock to the callers, but instead introduced a "sb_bread() with read_lock(&pointers_lock)" bug (which made this problem easier to hit). Al Viro suggested that why not to do like get_branch()/get_block()/ find_shared() in Minix filesystem does. And doing like that is almost a revert of "[PATCH] err1-40: sysvfs locking fix" except that get_branch() from with find_shared() is called without write_lock(&pointers_lock). Reported-by: syzbot <syzbot+69b40dc5fd40f32c199f@syzkaller.appspotmail.com> Link: https://syzkaller.appspot.com/bug?extid=69b40dc5fd40f32c199f Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Link: https://lore.kernel.org/r/0d195f93-a22a-49a2-0020-103534d6f7f6@I-love.SAKURA.ne.jp Signed-off-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> |
||
|---|---|---|
| .. | ||
| Kconfig | ||
| Makefile | ||
| balloc.c | ||
| dir.c | ||
| file.c | ||
| ialloc.c | ||
| inode.c | ||
| itree.c | ||
| namei.c | ||
| super.c | ||
| sysv.h | ||