4.14-stable review patch. If anyone has any objections, please let me know.
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From: Gustavo A. R. Silva gustavoars@kernel.org
commit eec679e4ac5f47507774956fb3479c206e761af7 upstream.
In a TLV encoding scheme, the Length part represents the length after the header containing the values for type and length. In this case, `tlv_len` should be:
tlv_len == (sizeof(*tlv_rxba) - 1) - sizeof(tlv_rxba->header) + tlv_bitmap_len
Notice that the `- 1` accounts for the one-element array `bitmap`, which 1-byte size is already included in `sizeof(*tlv_rxba)`.
So, if the above is correct, there is a double-counting of some members in `struct mwifiex_ie_types_rxba_sync`, when `tlv_buf_left` and `tmp` are calculated:
968 tlv_buf_left -= (sizeof(*tlv_rxba) + tlv_len); 969 tmp = (u8 *)tlv_rxba + tlv_len + sizeof(*tlv_rxba);
in specific, members:
drivers/net/wireless/marvell/mwifiex/fw.h:777 777 u8 mac[ETH_ALEN]; 778 u8 tid; 779 u8 reserved; 780 __le16 seq_num; 781 __le16 bitmap_len;
This is clearly wrong, and affects the subsequent decoding of data in `event_buf` through `tlv_rxba`:
970 tlv_rxba = (struct mwifiex_ie_types_rxba_sync *)tmp;
Fix this by using `sizeof(tlv_rxba->header)` instead of `sizeof(*tlv_rxba)` in the calculation of `tlv_buf_left` and `tmp`.
This results in the following binary differences before/after changes:
| drivers/net/wireless/marvell/mwifiex/11n_rxreorder.o | @@ -4698,11 +4698,11 @@ | drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c:968 | tlv_buf_left -= (sizeof(tlv_rxba->header) + tlv_len); | - 1da7: lea -0x11(%rbx),%edx | + 1da7: lea -0x4(%rbx),%edx | 1daa: movzwl %bp,%eax | drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c:969 | tmp = (u8 *)tlv_rxba + sizeof(tlv_rxba->header) + tlv_len; | - 1dad: lea 0x11(%r15,%rbp,1),%r15 | + 1dad: lea 0x4(%r15,%rbp,1),%r15
The above reflects the desired change: avoid counting 13 too many bytes; which is the total size of the double-counted members in `struct mwifiex_ie_types_rxba_sync`:
$ pahole -C mwifiex_ie_types_rxba_sync drivers/net/wireless/marvell/mwifiex/11n_rxreorder.o struct mwifiex_ie_types_rxba_sync { struct mwifiex_ie_types_header header; /* 0 4 */
|----------------------------------------------------------------------- | u8 mac[6]; /* 4 6 */ | | u8 tid; /* 10 1 */ | | u8 reserved; /* 11 1 */ | | __le16 seq_num; /* 12 2 */ | | __le16 bitmap_len; /* 14 2 */ | | u8 bitmap[1]; /* 16 1 */ | |----------------------------------------------------------------------| | 13 bytes| -----------
/* size: 17, cachelines: 1, members: 7 */ /* last cacheline: 17 bytes */ } __attribute__((__packed__));
Fixes: 99ffe72cdae4 ("mwifiex: process rxba_sync event") Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva gustavoars@kernel.org Reviewed-by: Kees Cook keescook@chromium.org Signed-off-by: Kalle Valo kvalo@kernel.org Link: https://lore.kernel.org/r/06668edd68e7a26bbfeebd1201ae077a2a7a8bce.169293195... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c +++ b/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c @@ -992,8 +992,8 @@ void mwifiex_11n_rxba_sync_event(struct } }
- tlv_buf_left -= (sizeof(*tlv_rxba) + tlv_len); - tmp = (u8 *)tlv_rxba + tlv_len + sizeof(*tlv_rxba); + tlv_buf_left -= (sizeof(tlv_rxba->header) + tlv_len); + tmp = (u8 *)tlv_rxba + sizeof(tlv_rxba->header) + tlv_len; tlv_rxba = (struct mwifiex_ie_types_rxba_sync *)tmp; } }