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authorPavel Skripkin <paskripkin@gmail.com>2021-08-13 18:14:33 +0300
committerDavid S. Miller <davem@davemloft.net>2021-08-16 13:08:05 +0300
commit19d1532a187669ce86d5a2696eb7275310070793 (patch)
tree6cfe659134260876b5e31eb3e4cc43e14631aa7c /drivers
parent5f773519639041faed4132f5943d7895f9078a4c (diff)
downloadlinux-19d1532a187669ce86d5a2696eb7275310070793.tar.xz
net: 6pack: fix slab-out-of-bounds in decode_data
Syzbot reported slab-out-of bounds write in decode_data(). The problem was in missing validation checks. Syzbot's reproducer generated malicious input, which caused decode_data() to be called a lot in sixpack_decode(). Since rx_count_cooked is only 400 bytes and noone reported before, that 400 bytes is not enough, let's just check if input is malicious and complain about buffer overrun. Fail log: ================================================================== BUG: KASAN: slab-out-of-bounds in drivers/net/hamradio/6pack.c:843 Write of size 1 at addr ffff888087c5544e by task kworker/u4:0/7 CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.6.0-rc3-syzkaller #0 ... Workqueue: events_unbound flush_to_ldisc Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:641 __asan_report_store1_noabort+0x17/0x20 mm/kasan/generic_report.c:137 decode_data.part.0+0x23b/0x270 drivers/net/hamradio/6pack.c:843 decode_data drivers/net/hamradio/6pack.c:965 [inline] sixpack_decode drivers/net/hamradio/6pack.c:968 [inline] Reported-and-tested-by: syzbot+fc8cd9a673d4577fb2e4@syzkaller.appspotmail.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/hamradio/6pack.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
index fcf3af76b6d7..8fe8887d506a 100644
--- a/drivers/net/hamradio/6pack.c
+++ b/drivers/net/hamradio/6pack.c
@@ -827,6 +827,12 @@ static void decode_data(struct sixpack *sp, unsigned char inbyte)
return;
}
+ if (sp->rx_count_cooked + 2 >= sizeof(sp->cooked_buf)) {
+ pr_err("6pack: cooked buffer overrun, data loss\n");
+ sp->rx_count = 0;
+ return;
+ }
+
buf = sp->raw_buf;
sp->cooked_buf[sp->rx_count_cooked++] =
buf[0] | ((buf[1] << 2) & 0xc0);