diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2020-03-04 11:28:31 +0100 |
|---|---|---|
| committer | Panwar Vijay Kumar <pvijayku@codeaurora.org> | 2021-09-28 13:53:25 +0530 |
| commit | 228bbfb250329a8e39c3e3b07a345c239d171aff (patch) | |
| tree | 407a791f78fbd521f8474fad406aa5335291258f /include/linux | |
| parent | 7504736e87258b542aeedf47460364b30b8cb79d (diff) | |
futex: Fix inode life-time issue
commit 8019ad13ef7f64be44d4f892af9c840179009254 upstream.
As reported by Jann, ihold() does not in fact guarantee inode
persistence. And instead of making it so, replace the usage of inode
pointers with a per boot, machine wide, unique inode identifier.
This sequence number is global, but shared (file backed) futexes are
rare enough that this should not become a performance issue.
Reported-by: Jann Horn <jannh@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit:24bbfe34bb44c036c3a0874bf74fc2387d5557bf
Git-repo: https://android.googlesource.com/kernel/common/
Change-Id: I2c28eac963cef6ed8b389fbdb079e355e3c36cc0
Signed-off-by: pvijayku <pvijayku@codeaurora.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/fs.h | 1 | ||||
| -rw-r--r-- | include/linux/futex.h | 17 |
2 files changed, 11 insertions, 7 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 66360a2f97bc..cb599dd90018 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -689,6 +689,7 @@ struct inode { struct rcu_head i_rcu; }; u64 i_version; + atomic64_t i_sequence; /* see futex */ atomic_t i_count; atomic_t i_dio_count; atomic_t i_writecount; diff --git a/include/linux/futex.h b/include/linux/futex.h index 6435f46d6e13..c015fa91e7cc 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -34,23 +34,26 @@ handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi); union futex_key { struct { + u64 i_seq; unsigned long pgoff; - struct inode *inode; - int offset; + unsigned int offset; } shared; struct { + union { + struct mm_struct *mm; + u64 __tmp; + }; unsigned long address; - struct mm_struct *mm; - int offset; + unsigned int offset; } private; struct { + u64 ptr; unsigned long word; - void *ptr; - int offset; + unsigned int offset; } both; }; -#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } } +#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = 0ULL } } #ifdef CONFIG_FUTEX extern void exit_robust_list(struct task_struct *curr); |