On Tue, Jul 16, 2024 at 07:36:40AM -0700, Kees Cook wrote:
>
>
> 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>
Tested-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
I have no preference between the two, but it would be really nice if a
fix were to hit both -next and mainline sooner rather than later. ;-)
Thanx, Paul
