diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-10-24 09:48:33 -1000 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-10-24 09:48:33 -1000 |
| commit | 87066fdd2e30fe9dd531125d95257c118a74617e (patch) | |
| tree | 889339bdce44c612c179d28ab9209978e85eef48 | |
| parent | b20078fd69a3da08d85c79b95101cf25c4afcc97 (diff) | |
Revert "mm/secretmem: use refcount_t instead of atomic_t"
This reverts commit 110860541f443f950c1274f217a1a3e298670a33.
Converting the "secretmem_users" counter to a refcount is incorrect,
because a refcount is special in zero and can't just be incremented (but
a count of users is not, and "no users" is actually perfectly valid and
not a sign of a free'd resource).
Reported-by: syzbot+75639e6a0331cd61d3e2@syzkaller.appspotmail.com
Cc: Jordy Zomer <jordy@pwning.systems>
Cc: Kees Cook <keescook@chromium.org>,
Cc: Jordy Zomer <jordy@jordyzomer.github.io>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/secretmem.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/mm/secretmem.c b/mm/secretmem.c index 1fea68b8d5a6..030f02ddc7c1 100644 --- a/mm/secretmem.c +++ b/mm/secretmem.c @@ -18,7 +18,6 @@ #include <linux/secretmem.h> #include <linux/set_memory.h> #include <linux/sched/signal.h> -#include <linux/refcount.h> #include <uapi/linux/magic.h> @@ -41,11 +40,11 @@ module_param_named(enable, secretmem_enable, bool, 0400); MODULE_PARM_DESC(secretmem_enable, "Enable secretmem and memfd_secret(2) system call"); -static refcount_t secretmem_users; +static atomic_t secretmem_users; bool secretmem_active(void) { - return !!refcount_read(&secretmem_users); + return !!atomic_read(&secretmem_users); } static vm_fault_t secretmem_fault(struct vm_fault *vmf) @@ -104,7 +103,7 @@ static const struct vm_operations_struct secretmem_vm_ops = { static int secretmem_release(struct inode *inode, struct file *file) { - refcount_dec(&secretmem_users); + atomic_dec(&secretmem_users); return 0; } @@ -218,7 +217,7 @@ SYSCALL_DEFINE1(memfd_secret, unsigned int, flags) file->f_flags |= O_LARGEFILE; fd_install(fd, file); - refcount_inc(&secretmem_users); + atomic_inc(&secretmem_users); return fd; err_put_fd: |