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570d7a98e7
sys_move_mount() crashes by dereferencing the pointer MNT_NS_INTERNAL,
a.k.a. ERR_PTR(-EINVAL), if the old mount is specified by fd for a
kernel object with an internal mount, such as a pipe or memfd.
Fix it by checking for this case and returning -EINVAL.
[AV: what we want is is_mounted(); use that instead of making the
condition even more convoluted]
Reproducer:
#include <unistd.h>
#define __NR_move_mount 429
#define MOVE_MOUNT_F_EMPTY_PATH 0x00000004
int main()
{
int fds[2];
pipe(fds);
syscall(__NR_move_mount, fds[0], "", -1, "/", MOVE_MOUNT_F_EMPTY_PATH);
}
Reported-by: syzbot+6004acbaa1893ad013f0@syzkaller.appspotmail.com
Fixes: 2db154b3ea ("vfs: syscall: Add move_mount(2) to move mounts around")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Linux kernel
============
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There are various text files in the Documentation/ subdirectory,
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Please read the Documentation/process/changes.rst file, as it contains the
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