On July 16, 2024 7:03:55 AM PDT, Jeff Johnson <quic_jjohnson@xxxxxxxxxxx> wrote:
>On 7/16/2024 7:00 AM, Jeff Johnson wrote:
>> On 7/16/2024 4:06 AM, Paolo Abeni wrote:
>>> gcc 11.4.1-3 warns about memcpy() with overlapping pointers:
>>>
>>> drivers/net/wireless/ath/ath12k/wow.c: In function ‘ath12k_wow_convert_8023_to_80211.constprop’:
>>> ./include/linux/fortify-string.h:114:33: error: ‘__builtin_memcpy’ accessing 18446744073709551611 or more bytes at offsets 0 and 0 overlaps 9223372036854775799 bytes at offset -9223372036854775804 [-Werror=restrict]
>>> 114 | #define __underlying_memcpy __builtin_memcpy
>>> | ^
>>> ./include/linux/fortify-string.h:637:9: note: in expansion of macro ‘__underlying_memcpy’
>>> 637 | __underlying_##op(p, q, __fortify_size); \
>>> | ^~~~~~~~~~~~~
>>> ./include/linux/fortify-string.h:682:26: note: in expansion of macro ‘__fortify_memcpy_chk’
>>> 682 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \
>>> | ^~~~~~~~~~~~~~~~~~~~
>>> drivers/net/wireless/ath/ath12k/wow.c:190:25: note: in expansion of macro ‘memcpy’
>>> 190 | memcpy(pat, eth_pat, eth_pat_len);
>>> | ^~~~~~
>>> ./include/linux/fortify-string.h:114:33: error: ‘__builtin_memcpy’ accessing 18446744073709551605 or more bytes at offsets 0 and 0 overlaps 9223372036854775787 bytes at offset -9223372036854775798 [-Werror=restrict]
>>> 114 | #define __underlying_memcpy __builtin_memcpy
>>> | ^
>>> ./include/linux/fortify-string.h:637:9: note: in expansion of macro ‘__underlying_memcpy’
>>> 637 | __underlying_##op(p, q, __fortify_size); \
>>> | ^~~~~~~~~~~~~
>>> ./include/linux/fortify-string.h:682:26: note: in expansion of macro ‘__fortify_memcpy_chk’
>>> 682 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \
>>> | ^~~~~~~~~~~~~~~~~~~~
>>> drivers/net/wireless/ath/ath12k/wow.c:232:25: note: in expansion of macro ‘memcpy’
>>> 232 | memcpy(pat, eth_pat, eth_pat_len);
>>> | ^~~~~~
>>>
>>> The sum of size_t operands can overflow SIZE_MAX, triggering the
>>> warning.
>>> Address the issue using the suitable helper.
>>>
>>> Fixes: 4a3c212eee0e ("wifi: ath12k: add basic WoW functionalities")
>>> Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
>>> ---
>>> Only built tested. Sending directly to net to reduce the RTT, but no
>>> objections to go through the WiFi tree first
>>> ---
>>> drivers/net/wireless/ath/ath12k/wow.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/net/wireless/ath/ath12k/wow.c b/drivers/net/wireless/ath/ath12k/wow.c
>>> index c5cba825a84a..bead19db2c9a 100644
>>> --- a/drivers/net/wireless/ath/ath12k/wow.c
>>> +++ b/drivers/net/wireless/ath/ath12k/wow.c
>>> @@ -186,7 +186,7 @@ ath12k_wow_convert_8023_to_80211(struct ath12k *ar,
>>> if (eth_pkt_ofs < ETH_ALEN) {
>>> pkt_ofs = eth_pkt_ofs + a1_ofs;
>>>
>>> - if (eth_pkt_ofs + eth_pat_len < ETH_ALEN) {
>>> + if (size_add(eth_pkt_ofs, eth_pat_len) < ETH_ALEN) {
>>> memcpy(pat, eth_pat, eth_pat_len);
>>> memcpy(bytemask, eth_bytemask, eth_pat_len);
>>>
>>> @@ -228,7 +228,7 @@ ath12k_wow_convert_8023_to_80211(struct ath12k *ar,
>>> } else if (eth_pkt_ofs < prot_ofs) {
>>> pkt_ofs = eth_pkt_ofs - ETH_ALEN + a3_ofs;
>>>
>>> - if (eth_pkt_ofs + eth_pat_len < prot_ofs) {
>>> + if (size_add(eth_pkt_ofs, eth_pat_len) < prot_ofs) {
>>> memcpy(pat, eth_pat, eth_pat_len);
>>> memcpy(bytemask, eth_bytemask, eth_pat_len);
>>>
>>
>> Duplicate of https://msgid.link/20240704144341.207317-1-kvalo@xxxxxxxxxx ??
>
>Let me add Kees & Paul to see if they prefer your solution
Heh, yeah, that works too! Avoid the overflow via saturating addition.
Reviewed-by: Kees Cook<kees@xxxxxxxxxx>
--
Kees Cook
