From: Johannes Berg <johannes.berg@xxxxxxxxx> [ Upstream commit 9ad7974856926129f190ffbe3beea78460b3b7cc ] If it looks like there's another subframe in the A-MSDU but the header isn't fully there, we can end up reading data out of bounds, only to discard later. Make this a bit more careful and check if the subframe header can even be present. Reported-by: syzbot+d050d437fe47d479d210@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://msgid.link/20240226203405.a731e2c95e38.I82ce7d8c0cc8970ce29d0a39fdc07f1ffc425be4@changeid Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- net/wireless/util.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/net/wireless/util.c b/net/wireless/util.c index d1ce3bee27973..b9d15f369378b 100644 --- a/net/wireless/util.c +++ b/net/wireless/util.c @@ -791,15 +791,19 @@ ieee80211_amsdu_subframe_length(void *field, u8 mesh_flags, u8 hdr_type) bool ieee80211_is_valid_amsdu(struct sk_buff *skb, u8 mesh_hdr) { - int offset = 0, remaining, subframe_len, padding; + int offset = 0, subframe_len, padding; for (offset = 0; offset < skb->len; offset += subframe_len + padding) { + int remaining = skb->len - offset; struct { __be16 len; u8 mesh_flags; } hdr; u16 len; + if (sizeof(hdr) > remaining) + return false; + if (skb_copy_bits(skb, offset + 2 * ETH_ALEN, &hdr, sizeof(hdr)) < 0) return false; @@ -807,7 +811,6 @@ bool ieee80211_is_valid_amsdu(struct sk_buff *skb, u8 mesh_hdr) mesh_hdr); subframe_len = sizeof(struct ethhdr) + len; padding = (4 - subframe_len) & 0x3; - remaining = skb->len - offset; if (subframe_len > remaining) return false; @@ -825,7 +828,7 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list, { unsigned int hlen = ALIGN(extra_headroom, 4); struct sk_buff *frame = NULL; - int offset = 0, remaining; + int offset = 0; struct { struct ethhdr eth; uint8_t flags; @@ -839,10 +842,14 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list, copy_len = sizeof(hdr); while (!last) { + int remaining = skb->len - offset; unsigned int subframe_len; int len, mesh_len = 0; u8 padding; + if (copy_len > remaining) + goto purge; + skb_copy_bits(skb, offset, &hdr, copy_len); if (iftype == NL80211_IFTYPE_MESH_POINT) mesh_len = __ieee80211_get_mesh_hdrlen(hdr.flags); @@ -852,7 +859,6 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list, padding = (4 - subframe_len) & 0x3; /* the last MSDU has no padding */ - remaining = skb->len - offset; if (subframe_len > remaining) goto purge; /* mitigate A-MSDU aggregation injection attacks */ -- 2.43.0
