6.15-stable review patch. If anyone has any objections, please let me know.
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From: Kees Cook kees@kernel.org
[ Upstream commit 368556dd234dc4a506a35a0c99c0eee2ab475c77 ]
The nested loop in iwl_mld_send_proto_offload() confuses Clang into thinking there could be a final loop iteration past the end of the "nsc" array (which is only 4 entries). The FORTIFY checking in memcmp() (via ipv6_addr_cmp()) notices this (due to the available bytes in the out-of-bounds position of &nsc[4] being 0), and errors out, failing the build. For some reason (likely due to architectural loop unrolling configurations), this is only exposed on ARM builds currently. Due to Clang's lack of inline tracking[1], the warning is not very helpful:
include/linux/fortify-string.h:719:4: error: call to '__read_overflow' declared with 'error' attribute: detected read beyond size of object (1st parameter) 719 | __read_overflow(); | ^ 1 error generated.
But this was tracked down to iwl_mld_send_proto_offload()'s ipv6_addr_cmp() call.
An upstream Clang bug has been filed[2] to track this. For now fix the build by explicitly bounding the inner loop by "n_nsc", which is what "c" is already limited to.
Reported-by: Nathan Chancellor nathan@kernel.org Closes: https://github.com/ClangBuiltLinux/linux/issues/2076 Link: https://github.com/llvm/llvm-project/pull/73552 [1] Link: https://github.com/llvm/llvm-project/issues/136603 [2] Link: https://lore.kernel.org/r/20250421204153.work.935-kees@kernel.org Signed-off-by: Kees Cook kees@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/wireless/intel/iwlwifi/mld/d3.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wireless/intel/iwlwifi/mld/d3.c b/drivers/net/wireless/intel/iwlwifi/mld/d3.c index ee99298eebf59..7ce01ad3608e1 100644 --- a/drivers/net/wireless/intel/iwlwifi/mld/d3.c +++ b/drivers/net/wireless/intel/iwlwifi/mld/d3.c @@ -1757,7 +1757,7 @@ iwl_mld_send_proto_offload(struct iwl_mld *mld,
addrconf_addr_solict_mult(&wowlan_data->target_ipv6_addrs[i], &solicited_addr); - for (j = 0; j < c; j++) + for (j = 0; j < n_nsc && j < c; j++) if (ipv6_addr_cmp(&nsc[j].dest_ipv6_addr, &solicited_addr) == 0) break;