"value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Mark bpf prog stack with kmsan_unposion_memory in interpreter mode\n\nsyzbot reported uninit memory usages during map_{lookup,delete}_elem.\n\n==========\nBUG: KMSAN: uninit-value in __dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline]\nBUG: KMSAN: uninit-value in dev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796\n__dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline]\ndev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796\n____bpf_map_lookup_elem kernel/bpf/helpers.c:42 [inline]\nbpf_map_lookup_elem+0x5c/0x80 kernel/bpf/helpers.c:38\n___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997\n__bpf_prog_run256+0xb5/0xe0 kernel/bpf/core.c:2237\n==========\n\nThe reproducer should be in the interpreter mode.\n\nThe C reproducer is trying to run the following bpf prog:\n\n 0: (18) r0 = 0x0\n 2: (18) r1 = map[id:49]\n 4: (b7) r8 = 16777216\n 5: (7b) *(u64 *)(r10 -8) = r8\n 6: (bf) r2 = r10\n 7: (07) r2 += -229\n ^^^^^^^^^^\n\n 8: (b7) r3 = 8\n 9: (b7) r4 = 0\n 10: (85) call dev_map_lookup_elem#1543472\n 11: (95) exit\n\nIt is due to the \"void *key\" (r2) passed to the helper. bpf allows uninit\nstack memory access for bpf prog with the right privileges. This patch\nuses kmsan_unpoison_memory() to mark the stack as initialized.\n\nThis should address different syzbot reports on the uninit \"void *key\"\nargument during map_{lookup,delete}_elem."
