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author | Peter Zijlstra <peterz@infradead.org> | 2020-03-04 13:28:31 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-03-25 10:06:14 +0300 |
commit | e6d506cd2243aa8f6e19fdb4dc61d85275c2c918 (patch) | |
tree | 3dd4a5b1323ad9761fac57ba2fcfdd38abeb58cc /include/linux/futex.h | |
parent | af6bdc2a85a9078b88bb3922ebd7d0caa2e0a52c (diff) | |
download | linux-e6d506cd2243aa8f6e19fdb4dc61d85275c2c918.tar.xz |
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>
Diffstat (limited to 'include/linux/futex.h')
-rw-r--r-- | include/linux/futex.h | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/include/linux/futex.h b/include/linux/futex.h index ccaef0097785..a61bf436dcf3 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -29,23 +29,26 @@ struct task_struct; 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); |