From 1b70fdf9621f7090b73e332575b2a37b9d3f3b1b Mon Sep 17 00:00:00 2001 From: Erick Archer Date: Sat, 27 Apr 2024 17:05:56 +0200 Subject: [PATCH] Input: ff-core - prefer struct_size over open coded arithmetic BugLink: https://bugs.launchpad.net/bugs/2077600 [ Upstream commit a08b8f8557ad88ffdff8905e5da972afe52e3307 ] This is an effort to get rid of all multiplications from allocation functions in order to prevent integer overflows [1][2]. As the "ff" variable is a pointer to "struct ff_device" and this structure ends in a flexible array: struct ff_device { [...] struct file *effect_owners[] __counted_by(max_effects); }; the preferred way in the kernel is to use the struct_size() helper to do the arithmetic instead of the calculation "size + count * size" in the kzalloc() function. The struct_size() helper returns SIZE_MAX on overflow. So, refactor the comparison to take advantage of this. This way, the code is more readable and safer. This code was detected with the help of Coccinelle, and audited and modified manually. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1] Link: https://github.com/KSPP/linux/issues/160 [2] Signed-off-by: Erick Archer Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/AS8PR02MB72371E646714BAE2E51A6A378B152@AS8PR02MB7237.eurprd02.prod.outlook.com Signed-off-by: Dmitry Torokhov Signed-off-by: Sasha Levin Signed-off-by: Portia Stephens Signed-off-by: Roxana Nicolescu --- drivers/input/ff-core.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/input/ff-core.c b/drivers/input/ff-core.c index 16231fe080b0..609a5f01761b 100644 --- a/drivers/input/ff-core.c +++ b/drivers/input/ff-core.c @@ -9,8 +9,10 @@ /* #define DEBUG */ #include +#include #include #include +#include #include #include @@ -315,9 +317,8 @@ int input_ff_create(struct input_dev *dev, unsigned int max_effects) return -EINVAL; } - ff_dev_size = sizeof(struct ff_device) + - max_effects * sizeof(struct file *); - if (ff_dev_size < max_effects) /* overflow */ + ff_dev_size = struct_size(ff, effect_owners, max_effects); + if (ff_dev_size == SIZE_MAX) /* overflow */ return -EINVAL; ff = kzalloc(ff_dev_size, GFP_KERNEL);