From: Kalle Valo <kvalo@kernel.org>
To: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Amitkumar Karwar <amitkarwar@gmail.com>,
Ganapathi Bhat <ganapathi017@gmail.com>,
Sharvari Harisangam <sharvari.harisangam@nxp.com>,
Xinming Hu <huxinming820@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org,
netdev@vger.kernel.org,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH][next] wifi: mwifiex: Replace one-element array with flexible-array member
Date: Mon, 13 Feb 2023 16:53:32 +0000 (UTC) [thread overview]
Message-ID: <167630721096.12830.15488375975791023564.kvalo@kernel.org> (raw)
In-Reply-To: <Y9xkjXeElSEQ0FPY@work>
"Gustavo A. R. Silva" <gustavoars@kernel.org> wrote:
> One-element arrays are deprecated, and we are replacing them with flexible
> array members instead. So, replace one-element array with flexible-array
> member in struct mwifiex_ie_types_rates_param_set.
>
> These are the only binary differences I see after the change:
>
> mwifiex.o
> _@@ -50154,7 +50154,7 @@
> 23514: R_X86_64_32S kmalloc_caches+0x50
> 23518: call 2351d <mwifiex_scan_networks+0x11d>
> 23519: R_X86_64_PLT32 __tsan_read8-0x4
> - 2351d: mov $0x225,%edx
> + 2351d: mov $0x224,%edx
> 23522: mov $0xdc0,%esi
> 23527: mov 0x0(%rip),%rdi # 2352e <mwifiex_scan_networks+0x12e>
> 2352a: R_X86_64_PC32 kmalloc_caches+0x4c
> scan.o
> _@@ -5582,7 +5582,7 @@
> 4394: R_X86_64_32S kmalloc_caches+0x50
> 4398: call 439d <mwifiex_scan_networks+0x11d>
> 4399: R_X86_64_PLT32 __tsan_read8-0x4
> - 439d: mov $0x225,%edx
> + 439d: mov $0x224,%edx
> 43a2: mov $0xdc0,%esi
> 43a7: mov 0x0(%rip),%rdi # 43ae <mwifiex_scan_networks+0x12e>
> 43aa: R_X86_64_PC32 kmalloc_caches+0x4c
>
> and the reason for that is the following line:
>
> drivers/net/wireless/marvell/mwifiex/scan.c:
> 1517 scan_cfg_out = kzalloc(sizeof(union mwifiex_scan_cmd_config_tlv),
> 1518 GFP_KERNEL);
>
> sizeof(union mwifiex_scan_cmd_config_tlv) is now one-byte smaller due to the
> flex-array transformation:
>
> 46 union mwifiex_scan_cmd_config_tlv {
> 47 /* Scan configuration (variable length) */
> 48 struct mwifiex_scan_cmd_config config;
> 49 /* Max allocated block */
> 50 u8 config_alloc_buf[MAX_SCAN_CFG_ALLOC];
> 51 };
>
> Notice that MAX_SCAN_CFG_ALLOC is defined in terms of
> sizeof(struct mwifiex_ie_types_rates_param_set), see:
>
> 26 /* Memory needed to store supported rate */
> 27 #define RATE_TLV_MAX_SIZE (sizeof(struct mwifiex_ie_types_rates_param_set) \
> 28 + HOSTCMD_SUPPORTED_RATES)
>
> 37 /* Maximum memory needed for a mwifiex_scan_cmd_config with all TLVs at max */
> 38 #define MAX_SCAN_CFG_ALLOC (sizeof(struct mwifiex_scan_cmd_config) \
> 39 + sizeof(struct mwifiex_ie_types_num_probes) \
> 40 + sizeof(struct mwifiex_ie_types_htcap) \
> 41 + CHAN_TLV_MAX_SIZE \
> 42 + RATE_TLV_MAX_SIZE \
> 43 + WILDCARD_SSID_TLV_MAX_SIZE)
>
> This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> routines on memcpy() and help us make progress towards globally
> enabling -fstrict-flex-arrays=3 [1].
>
> Link: https://github.com/KSPP/linux/issues/79
> Link: https://github.com/KSPP/linux/issues/252
> Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1]
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> Reviewed-by: Kees Cook <keescook@chromium.org>
Patch applied to wireless-next.git, thanks.
235fd607c6cb wifi: mwifiex: Replace one-element array with flexible-array member
--
https://patchwork.kernel.org/project/linux-wireless/patch/Y9xkjXeElSEQ0FPY@work/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
prev parent reply other threads:[~2023-02-13 16:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-03 1:34 [PATCH][next] wifi: mwifiex: Replace one-element array with flexible-array member Gustavo A. R. Silva
2023-02-03 17:57 ` Kees Cook
2023-02-13 16:53 ` Kalle Valo [this message]
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