For the bpf syscall, we are relying on the compiler to properly zero out the bpf_attr union that we copy userspace data into. Unfortunately that doesn't always work properly, padding and other oddities might not be correctly zeroed, and in some tests odd things have been found when the stack is pre-initialized to other values. Fix this by explicitly memsetting the structure to 0 before using it. Reported-by: Maciej Żenczykowski <maze@xxxxxxxxxx> Reported-by: John Stultz <john.stultz@xxxxxxxxxx> Reported-by: Alexander Potapenko <glider@xxxxxxxxxx> Reported-by: Alistair Delva <adelva@xxxxxxxxxx> Cc: stable <stable@xxxxxxxxxxxxxxx> Link: https://android-review.googlesource.com/c/kernel/common/+/1235490 Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/bpf/syscall.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index a91ad518c050..a4b1de8ea409 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3354,7 +3354,7 @@ static int bpf_map_do_batch(const union bpf_attr *attr, SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size) { - union bpf_attr attr = {}; + union bpf_attr attr; int err; if (sysctl_unprivileged_bpf_disabled && !capable(CAP_SYS_ADMIN)) @@ -3366,6 +3366,7 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz size = min_t(u32, size, sizeof(attr)); /* copy attributes from user space, may be less than sizeof(bpf_attr) */ + memset(&attr, 0, sizeof(attr)); if (copy_from_user(&attr, uattr, size) != 0) return -EFAULT; base-commit: 6c90b86a745a446717fdf408c4a8a4631a5e8ee3 -- 2.25.2
