When kattr->test.data_size_in > INT_MAX, signed min_t will assign
negative value to data_len. This negative value then gets passed
over to copy_from_user where it is converted to (big) unsigned.
Use unsigned min_t to avoid this overflow.
usercopy: Kernel memory overwrite attempt detected to wrapped address
(offset 0, size 18446612140539162846)!
------------[ cut here ]------------
kernel BUG at mm/usercopy.c:102!
invalid opcode: 0000 [#1] SMP KASAN
Modules linked in:
CPU: 0 PID: 3781 Comm: syz-executor226 Not tainted 4.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:usercopy_abort+0xbd/0xbf mm/usercopy.c:102
RSP: 0018:ffff8801e9703a38 EFLAGS: 00010286
RAX: 000000000000006c RBX: ffffffff84fc7040 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff816560a2 RDI: ffffed003d2e0739
RBP: ffff8801e9703a90 R08: 000000000000006c R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff84fc73a0
R13: ffffffff84fc7180 R14: ffffffff84fc7040 R15: ffffffff84fc7040
FS: 00007f54e0bec300(0000) GS:ffff8801f6600000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000280 CR3: 00000001e90ea000 CR4: 00000000003426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
check_bogus_address mm/usercopy.c:155 [inline]
__check_object_size mm/usercopy.c:263 [inline]
__check_object_size.cold+0x8c/0xad mm/usercopy.c:253
check_object_size include/linux/thread_info.h:112 [inline]
check_copy_size include/linux/thread_info.h:143 [inline]
copy_from_user include/linux/uaccess.h:142 [inline]
bpf_prog_test_run_xdp+0xe57/0x1240 net/bpf/test_run.c:989
bpf_prog_test_run kernel/bpf/syscall.c:3377 [inline]
__sys_bpf+0xdf2/0x4a50 kernel/bpf/syscall.c:4679
SYSC_bpf kernel/bpf/syscall.c:4765 [inline]
SyS_bpf+0x26/0x50 kernel/bpf/syscall.c:4763
do_syscall_64+0x21a/0x3e0 arch/x86/entry/common.c:305
entry_SYSCALL_64_after_hwframe+0x46/0xbb
Cc: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
Fixes: 1c1949982524 ("bpf: introduce frags support to bpf_prog_test_run_xdp()")
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
---
net/bpf/test_run.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 0220b0822d77..5819a7a5e3c6 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -960,7 +960,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
while (size < kattr->test.data_size_in) {
struct page *page;
skb_frag_t *frag;
- int data_len;
+ u32 data_len;
if (sinfo->nr_frags == MAX_SKB_FRAGS) {
ret = -ENOMEM;
@@ -976,7 +976,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
frag = &sinfo->frags[sinfo->nr_frags++];
__skb_frag_set_page(frag, page);
- data_len = min_t(int, kattr->test.data_size_in - size,
+ data_len = min_t(u32, kattr->test.data_size_in - size,
PAGE_SIZE);
skb_frag_size_set(frag, data_len);
--
2.35.0.263.gb82422642f-goog
