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Sat, 26 Apr 2025 13:32:45 +0200 Message-ID: Date: Sat, 26 Apr 2025 13:32:44 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] video: fbdev: arkfb: Cast ics5342_init() allocation type To: Kees Cook Cc: Javier Martinez Canillas , Thomas Zimmermann , Zheyu Ma , Samuel Thibault , Jiapeng Chong , linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org References: <20250426062305.work.819-kees@kernel.org> Content-Language: en-US From: Helge Deller Autocrypt: addr=deller@gmx.de; keydata= xsFNBF3Ia3MBEAD3nmWzMgQByYAWnb9cNqspnkb2GLVKzhoH2QD4eRpyDLA/3smlClbeKkWT HLnjgkbPFDmcmCz5V0Wv1mKYRClAHPCIBIJgyICqqUZo2qGmKstUx3pFAiztlXBANpRECgwJ r+8w6mkccOM9GhoPU0vMaD/UVJcJQzvrxVHO8EHS36aUkjKd6cOpdVbCt3qx8cEhCmaFEO6u CL+k5AZQoABbFQEBocZE1/lSYzaHkcHrjn4cQjc3CffXnUVYwlo8EYOtAHgMDC39s9a7S90L 69l6G73lYBD/Br5lnDPlG6dKfGFZZpQ1h8/x+Qz366Ojfq9MuuRJg7ZQpe6foiOtqwKym/zV dVvSdOOc5sHSpfwu5+BVAAyBd6hw4NddlAQUjHSRs3zJ9OfrEx2d3mIfXZ7+pMhZ7qX0Axlq Lq+B5cfLpzkPAgKn11tfXFxP+hcPHIts0bnDz4EEp+HraW+oRCH2m57Y9zhcJTOJaLw4YpTY GRUlF076vZ2Hz/xMEvIJddRGId7UXZgH9a32NDf+BUjWEZvFt1wFSW1r7zb7oGCwZMy2LI/G aHQv/N0NeFMd28z+deyxd0k1CGefHJuJcOJDVtcE1rGQ43aDhWSpXvXKDj42vFD2We6uIo9D 1VNre2+uAxFzqqf026H6cH8hin9Vnx7p3uq3Dka/Y/qmRFnKVQARAQABzRxIZWxnZSBEZWxs ZXIgPGRlbGxlckBnbXguZGU+wsGRBBMBCAA7AhsDBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheA FiEERUSCKCzZENvvPSX4Pl89BKeiRgMFAl3J1zsCGQEACgkQPl89BKeiRgNK7xAAg6kJTPje uBm9PJTUxXaoaLJFXbYdSPfXhqX/BI9Xi2VzhwC2nSmizdFbeobQBTtRIz5LPhjk95t11q0s uP5htzNISPpwxiYZGKrNnXfcPlziI2bUtlz4ke34cLK6MIl1kbS0/kJBxhiXyvyTWk2JmkMi REjR84lCMAoJd1OM9XGFOg94BT5aLlEKFcld9qj7B4UFpma8RbRUpUWdo0omAEgrnhaKJwV8 qt0ULaF/kyP5qbI8iA2PAvIjq73dA4LNKdMFPG7Rw8yITQ1Vi0DlDgDT2RLvKxEQC0o3C6O4 iQq7qamsThLK0JSDRdLDnq6Phv+Yahd7sDMYuk3gIdoyczRkXzncWAYq7XTWl7nZYBVXG1D8 gkdclsnHzEKpTQIzn/rGyZshsjL4pxVUIpw/vdfx8oNRLKj7iduf11g2kFP71e9v2PP94ik3 Xi9oszP+fP770J0B8QM8w745BrcQm41SsILjArK+5mMHrYhM4ZFN7aipK3UXDNs3vjN+t0zi qErzlrxXtsX4J6nqjs/mF9frVkpv7OTAzj7pjFHv0Bu8pRm4AyW6Y5/H6jOup6nkJdP/AFDu 5ImdlA0jhr3iLk9s9WnjBUHyMYu+HD7qR3yhX6uWxg2oB2FWVMRLXbPEt2hRGq09rVQS7DBy dbZgPwou7pD8MTfQhGmDJFKm2jvOwU0EXchrcwEQAOsDQjdtPeaRt8EP2pc8tG+g9eiiX9Sh rX87SLSeKF6uHpEJ3VbhafIU6A7hy7RcIJnQz0hEUdXjH774B8YD3JKnAtfAyuIU2/rOGa/v UN4BY6U6TVIOv9piVQByBthGQh4YHhePSKtPzK9Pv/6rd8H3IWnJK/dXiUDQllkedrENXrZp eLUjhyp94ooo9XqRl44YqlsrSUh+BzW7wqwfmu26UjmAzIZYVCPCq5IjD96QrhLf6naY6En3 ++tqCAWPkqKvWfRdXPOz4GK08uhcBp3jZHTVkcbo5qahVpv8Y8mzOvSIAxnIjb+cklVxjyY9 dVlrhfKiK5L+zA2fWUreVBqLs1SjfHm5OGuQ2qqzVcMYJGH/uisJn22VXB1c48yYyGv2HUN5 lC1JHQUV9734I5cczA2Gfo27nTHy3zANj4hy+s/q1adzvn7hMokU7OehwKrNXafFfwWVK3OG 1dSjWtgIv5KJi1XZk5TV6JlPZSqj4D8pUwIx3KSp0cD7xTEZATRfc47Yc+cyKcXG034tNEAc xZNTR1kMi9njdxc1wzM9T6pspTtA0vuD3ee94Dg+nDrH1As24uwfFLguiILPzpl0kLaPYYgB wumlL2nGcB6RVRRFMiAS5uOTEk+sJ/tRiQwO3K8vmaECaNJRfJC7weH+jww1Dzo0f1TP6rUa fTBRABEBAAHCwXYEGAEIACAWIQRFRIIoLNkQ2+89Jfg+Xz0Ep6JGAwUCXchrcwIbDAAKCRA+ Xz0Ep6JGAxtdEAC54NQMBwjUNqBNCMsh6WrwQwbg9tkJw718QHPw43gKFSxFIYzdBzD/YMPH l+2fFiefvmI4uNDjlyCITGSM+T6b8cA7YAKvZhzJyJSS7pRzsIKGjhk7zADL1+PJei9p9idy RbmFKo0dAL+ac0t/EZULHGPuIiavWLgwYLVoUEBwz86ZtEtVmDmEsj8ryWw75ZIarNDhV74s BdM2ffUJk3+vWe25BPcJiaZkTuFt+xt2CdbvpZv3IPrEkp9GAKof2hHdFCRKMtgxBo8Kao6p Ws/Vv68FusAi94ySuZT3fp1xGWWf5+1jX4ylC//w0Rj85QihTpA2MylORUNFvH0MRJx4mlFk XN6G+5jIIJhG46LUucQ28+VyEDNcGL3tarnkw8ngEhAbnvMJ2RTx8vGh7PssKaGzAUmNNZiG MB4mPKqvDZ02j1wp7vthQcOEg08z1+XHXb8ZZKST7yTVa5P89JymGE8CBGdQaAXnqYK3/yWf FwRDcGV6nxanxZGKEkSHHOm8jHwvQWvPP73pvuPBEPtKGLzbgd7OOcGZWtq2hNC6cRtsRdDx 4TAGMCz4j238m+2mdbdhRh3iBnWT5yPFfnv/2IjFAk+sdix1Mrr+LIDF++kiekeq0yUpDdc4 ExBy2xf6dd+tuFFBp3/VDN4U0UfG4QJ2fg19zE5Z8dS4jGIbLg== In-Reply-To: <20250426062305.work.819-kees@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:1S3zvciCiuaF2ZFFgka1cN5KYqrJSnPPfOQwlKCQhBbZYHbYNyA HQzYCk+2Z0HF3crIPsdsQFp62B3UdL3ieefJUsprM1biJpkEzOjC+qFxGf2ZjyNz4ybl4c3 xd4ZT/7gHzgc4Rro/W0XEBC9hpuYElU7gptkFJj8zhJuxwOSmuXfmT59MqlhlRimMiQheWM 899Wil/xfYzcI7Dxg4HlA== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:XEiqCWyyu34=;qlN/rJFu9tX5OmBgSmJrPCwuNFK 0jTK49Hx6J0bKlGg+WqqS+ro1mdxRYo3QWwMsAnW8nxHi7vDNJmj8odBCtIbzGI6KalXSSN7k 60SeKyH3khJid1+MK7ROS4hTfGqD2RkLr/1VZQklblP5CiCzjJ9avP/2RoomkvnS1peEebZXi HP1WLnzqcYR3spx4kl8c6zhxQ6I6QMeINt2SIwxHy7cBoVSbOhiHf81taEfE+BHuLwCUNDhCL arGcbFuYSSxPlkwt2ThrfHBs1FF5ujQKqCOtY9vPWFBdKEUa9yWeYQVP5wSnsociNFtwJTe95 yqLQ3oZMsDIU7ogpfRGWiIwOIzbFXaWSmNk+8UKlUALsmzykLmpF9oe1cNI6U4mzF+FMV4Xse HSPvDtoG9Mq3TGLn433hfMAi/4KS1RDcMeIRcMBDkRIaB/CqrJ/+8Iee/DfTSy5kVgam5IB5f qRZ2OV6ABJWYs7TC2giQXlMUYATjFwpPPIm90qmV6yTKwhg44S3J5p874ZKtgRcjUYOtGEUM6 mBdaelQsLc2/7PMyjaseLZdsTTSz6LqQOi0OCY0KPgDy6nR/foKPpRkibtTwtMg2IPL8F+PE/ UK+PyJust5sqqjwraxAJiBpsj3vX3cAVa3fz03qx92QJWjo/AU/gwtXEO71EZlvRNkFlj7Fxh TtvtLcbHKO8nxvgJbMcAAcGfnFMF0XDLo9Fwhr9WBJ1kvSOWKSOaI9k0KkwytxNUVvnNILcw4 A5fuj2qyYli8q+e4TK34v1+L0boI1JDfMDkRF0FYbIQm9WxvCjaDfdp4ktW66Yo9HbxGZL15Q RHI4d7tSTIdUzhH89sSw6GzgPxj8pGCRjcOfZA3GICBO9CXkK4dKe4+liPUBXBKoN1IZuMKWA hYuN6sNk02+1NCEh2oHbScE0AHb9olBR4nF5s6NXoPzP2yQIKVFbqds2vqFP63SpgPEJsBUKE r6lP3lRD9exPSNbqNur8JVjYSOgRuZe2n3+WPWjpNMS1LRXHQTx5xnx+nVZ5cOrTfq2O/WEpJ hKSqzQv1FQ5T56a3gosgsw7hAI3kSGma09xbInIy9lOS716ZM5K6jWVLuCxgPDhCw9QtuoegZ obbTQ94vAa3I5xogA/Fp/KBZGg4b0uPGlYxBFEqTUA8SmATOaC/kDxFuB5URCV0E/O2v5rXLk kJ/5xdfw666E2Xs06pgio2fUGbchgCmlPztogedTBbLdiwcp7vWHXEL8GBcHnwylYqpNfK7bD tmThCClvnmb6q6oEYifyNkpIHo9ip8kapS6NH7emQrqve2rGD378Fg1i6+xb6mzLpafQAJ8YF m9l387HQtvC/m8Vir+I8RwKV45ZuOsfyjJhNm0O8esLREySLJVAxz84/gIV9KB232dXOWs8MO TLlcmOhfbzMaa3wTRp1JA/puEaTxgrKAzCgrseH2XXKPEqn/i8YNz9uTTl85C4lm+AzMedcCk LOneZei1TUeWWEORTjmx9gZ0WB1DVxJRzS8EvN92eL9rGSoXuNB7EU6zq1X57X/iJ0T6SUrux 9Ln/fV04o6sMvhCuAT9ziwHHZLVk8VLYSa+9X0toGg0Y5N7rs98KD3b3NazJB9HKC0LfBvUwy 0+9atNvdcMllzNRD3hF9RRpC9deqXNZivhujxjjIWjojSqVCROlGOpG8dSj7zAIJjWJZHdChL M1X1hlrDdH7g/KB6R6Dm1K2IXioMBhZmNrJ40eYxq1I04xEo/4s3vjQu5lzANQoubvCLh3fxI QptBTbK/n1UA1EGgEnRATMznUCWZ7clBUdq3M5WEydzIgUvACB0W7KFIuSQlUBWJfb1bmfT0w 5i5ZvKwPgh9PK4box0D4ghXT/J06c70xAcRIolvBX3Hksq4roFXY2JGshSgFTHkYh/YTPg2pk nVt2bO/T+n3HA2foBt5fN5y1y16B1l21oXC41Go5Pazp8jTIhgrcbox87O+kCDhprEWaZQi7j ZMDc9q6+op/isHQGNO2KmObJboRAWG9QlKnbATtshjAI+PPzVey3PI4San4CizJcdYFEuVezi FW7WbS11H0/DZcIbfFxY93upJ3zrSzxv8sJ9D/IDz6xAgjQ2MahmGm/damey7/tj2OJeySHX+ QW31RB68fIb4UjosqSaujFxoUG/s+QjxjBKZBuTgfQsxDAr2eVJIzB6zxjeZVO+aDo/tyxPcd nD8wpSulDvC8WrWY+6jyBtubllpEcU3FZy/25+K4wAzdbKswealyKgBfXOVxYRP2Ggk2OSVWx MfHSOWp6rb3tJu7ZKyeuiBlNAm2KDtHJ79tfqu7Coq7HmVBS2t349ckwR4/7Unm+GxPyZKBow T5wBIUnv1wIN12OZTQX+uYfaylKJPqvVKeTST99eMeOJPL1qukIv6hAEW7BBhNFHZx9hd2SzQ s4zeBcRqqt/RES/7sdMPUAkEGRurb90twnuG8HpZ/8SYzbqC/WpBv8LO+KpRsqbX500XWWNva ZhReZmfQ3VSYEyu2IgnE8xvO8x0Zy0Cjp479PwZKTum1GvwOq3+SijCmlRTywjIKbeP4/LNTj TZc/UgaUDq7XaqFD3sAceRtMRyMooneblPwAqulOwBunxFYL3ZXMfPtUIIJuPEyheJOEpEyQF Af3PK+iVRSDYfGjH5TEiFCc7xzHCmAqQVgeezOgH7/A3/C5llxis4xeiJlfrk7E6iVpmJC7RB znvTpzBt47Qu+sCDWLhxD+ppJjEoDmRkYhy954+OmzslMYK6L8vAgGkNhEBmi23GxYsmhUSK1 i4VJznpel7bM1Wcq6RMbK0yfM0NJQIqZsGdcYah23fRC98GkrZw0lCcNaXDY0vpSjQhkc3VGA juDldBlcGbmekNG2fvN1XWZCKvQb88Y352OL9+5G7wsKkayhOFsIeKTGglsx/BMUaW7Rc1sjF Ix7+2CXRP3RcT1a9p3bhldVb09Ku6eDWttd1zd4u100e0MvnnJGEJO7MltC+Z5RgMA6w0WUAJ Mc3cyvFUpc0XfFEkygenxy1ZtXXvJlbzilIeuQa+rCczWHXu0CdVIT3bFUj2xf7ZNjOCfIE3I w== On 4/26/25 08:23, Kees Cook wrote: > In preparation for making the kmalloc family of allocators type aware, > we need to make sure that the returned type from the allocation matches > the type of the variable being assigned. (Before, the allocator would > always return "void *", which can be implicitly cast to any pointer type= .) >=20 > The assigned type is "struct dac_info *" but the returned type will be > "struct ics5342_info *", which has a larger allocation size. This is > by design, as struct ics5342_info contains struct dac_info as its first > member. Cast the allocation type to match the assignment. >=20 > Signed-off-by: Kees Cook Thanks Kees! I applied your patch, but wouldn't this untested patch be cleaner and fulf= ill the same purpose to match a kzalloc return type? diff --git a/drivers/video/fbdev/arkfb.c b/drivers/video/fbdev/arkfb.c index 7d131e3d159a..a57c8a992e11 100644 =2D-- a/drivers/video/fbdev/arkfb.c +++ b/drivers/video/fbdev/arkfb.c @@ -431,7 +431,8 @@ static struct dac_ops ics5342_ops =3D { =20 static struct dac_info * ics5342_init(dac_read_regs_t drr, dac_write_reg= s_t dwr, void *data) { - struct dac_info *info =3D (struct dac_info *)kzalloc(sizeof(struct= ics5342_info), GFP_KERNEL); + struct ics5342_info *ics_info =3D kzalloc(sizeof(struct ics5342_in= fo), GFP_KERNEL); + struct dac_info *info =3D &ics_info->dac; =20 if (! info) Helge --- > Cc: Helge Deller > Cc: Javier Martinez Canillas > Cc: Thomas Zimmermann > Cc: Zheyu Ma > Cc: Samuel Thibault > Cc: Jiapeng Chong > Cc: > Cc: > --- > drivers/video/fbdev/arkfb.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) >=20 > diff --git a/drivers/video/fbdev/arkfb.c b/drivers/video/fbdev/arkfb.c > index 082501feceb9..7d131e3d159a 100644 > --- a/drivers/video/fbdev/arkfb.c > +++ b/drivers/video/fbdev/arkfb.c > @@ -431,7 +431,7 @@ static struct dac_ops ics5342_ops =3D { > =20 > static struct dac_info * ics5342_init(dac_read_regs_t drr, dac_write_r= egs_t dwr, void *data) > { > - struct dac_info *info =3D kzalloc(sizeof(struct ics5342_info), GFP_KER= NEL); > + struct dac_info *info =3D (struct dac_info *)kzalloc(sizeof(struct ics= 5342_info), GFP_KERNEL); > =20 > if (! info) > return NULL;