I've got the following KASAN error while running test_bpf module on a powerpc 8xx (32 bits). That's reproductible, happens each time at the same test. Can someone help me to investigate and fix that ? [ 209.381037] test_bpf: #298 LD_IND byte frag [ 209.383041] Pass 1: shrink = 0, seen = 0x30000 [ 209.383284] Pass 2: shrink = 0, seen = 0x30000 [ 209.383562] flen=3 proglen=104 pass=3 image=8166dc91 from=modprobe pid=380 [ 209.383805] JIT code: 00000000: 7c 08 02 a6 90 01 00 04 91 c1 ff b8 91 e1 ff bc [ 209.384044] JIT code: 00000010: 94 21 ff 70 80 e3 00 58 81 e3 00 54 7d e7 78 50 [ 209.384279] JIT code: 00000020: 81 c3 00 a0 38 a0 00 00 38 80 00 00 38 a0 00 40 [ 209.384516] JIT code: 00000030: 3c e0 c0 02 60 e7 62 14 7c e8 03 a6 38 c5 00 00 [ 209.384753] JIT code: 00000040: 4e 80 00 21 41 80 00 0c 60 00 00 00 7c 83 23 78 [ 209.384990] JIT code: 00000050: 38 21 00 90 80 01 00 04 7c 08 03 a6 81 c1 ff b8 [ 209.385207] JIT code: 00000060: 81 e1 ff bc 4e 80 00 20 [ 209.385442] jited:1 [ 209.385762] ================================================================== [ 209.386272] BUG: KASAN: use-after-free in test_bpf_init+0x6f8/0xde8 [test_bpf] [ 209.386503] Read of size 4 at addr c2de70c0 by task modprobe/380 [ 209.386622] [ 209.386881] CPU: 0 PID: 380 Comm: modprobe Not tainted 5.10.0-rc5-s3k-dev-01341-g72d20eec3f8b #4178 [ 209.387032] Call Trace: [ 209.387404] [cad6b878] [c020e0d4] print_address_description.constprop.0+0x70/0x4e0 (unreliable) [ 209.387920] [cad6b8f8] [c020dc98] kasan_report+0x118/0x1c0 [ 209.388503] [cad6b938] [cb0e0c98] test_bpf_init+0x6f8/0xde8 [test_bpf] [ 209.388918] [cad6ba58] [c0004084] do_one_initcall+0xa4/0x33c [ 209.389377] [cad6bb28] [c00f9144] do_init_module+0x158/0x7f4 [ 209.389820] [cad6bbc8] [c00fccb0] load_module+0x3394/0x38d8 [ 209.390273] [cad6be38] [c00fd4e0] sys_finit_module+0x118/0x17c [ 209.390700] [cad6bf38] [c00170d0] ret_from_syscall+0x0/0x34 [ 209.391020] --- interrupt: c01 at 0xfd5e7c0 [ 209.395301] [ 209.395472] Allocated by task 276: [ 209.395767] __kasan_kmalloc.constprop.0+0xe8/0x134 [ 209.396029] kmem_cache_alloc+0x150/0x290 [ 209.396281] __alloc_skb+0x58/0x28c [ 209.396563] alloc_skb_with_frags+0x74/0x314 [ 209.396872] sock_alloc_send_pskb+0x404/0x424 [ 209.397205] unix_dgram_sendmsg+0x200/0xbf0 [ 209.397473] __sys_sendto+0x17c/0x21c [ 209.397754] ret_from_syscall+0x0/0x34 [ 209.397877] [ 209.398039] Freed by task 274: [ 209.398308] kasan_set_track+0x34/0x6c [ 209.398608] kasan_set_free_info+0x28/0x48 [ 209.398878] __kasan_slab_free+0x10c/0x19c [ 209.399141] kmem_cache_free+0x68/0x390 [ 209.399433] skb_free_datagram+0x20/0x8c [ 209.399759] unix_dgram_recvmsg+0x474/0x710 [ 209.400084] sock_read_iter+0x17c/0x228 [ 209.400348] vfs_read+0x3c8/0x4f4 [ 209.400603] ksys_read+0x17c/0x1cc [ 209.400878] ret_from_syscall+0x0/0x34 [ 209.401001] [ 209.401222] The buggy address belongs to the object at c2de70c0 [ 209.401222] which belongs to the cache skbuff_head_cache of size 176 [ 209.401462] The buggy address is located 0 bytes inside of [ 209.401462] 176-byte region [c2de70c0, c2de7170) [ 209.401604] The buggy address belongs to the page: [ 209.401867] page:464e6411 refcount:1 mapcount:0 mapping:00000000 index:0x0 pfn:0xb79 [ 209.402080] flags: 0x200(slab) [ 209.402477] raw: 00000200 00000100 00000122 c2004a90 00000000 00440088 ffffffff 00000001 [ 209.402646] page dumped because: kasan: bad access detected [ 209.402765] [ 209.402897] Memory state around the buggy address: [ 209.403142] c2de6f80: fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb fb [ 209.403388] c2de7000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 209.403639] >c2de7080: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb [ 209.403798] ^ [ 209.404048] c2de7100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc [ 209.404304] c2de7180: fc fc fc fc fc fc fa fb fb fb fb fb fb fb fb fb [ 209.404456] ================================================================== [ 209.404591] Disabling lock debugging due to kernel taint Thanks Christophe
