[PATCH] mtd: jedec_probe: use struct_size() helper for cfiq allocation

[PATCH] mtd: jedec_probe: use struct_size() helper for cfiq allocation

[Rahul Kumar]

Documentation/process/deprecated.rst recommends against performing
dynamic size calculations in the arguments of memory allocator
functions due to the risk of overflow. Such calculations can wrap
around and result in a smaller allocation than expected.

Replace the size calculation in cfiq allocation with struct_size()
helper to make the code clearer and handle overflows correctly.

Signed-off-by: Rahul Kumar <rk0006818@gmail.com>
---
 drivers/mtd/chips/jedec_probe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/chips/jedec_probe.c b/drivers/mtd/chips/jedec_probe.c
index 23c32fe584b7..a5d1137ca5ab 100644
--- a/drivers/mtd/chips/jedec_probe.c
+++ b/drivers/mtd/chips/jedec_probe.c
@@ -1985,7 +1985,7 @@ static int cfi_jedec_setup(struct map_info *map, struct cfi_private *cfi, int in
 
 	num_erase_regions = jedec_table[index].nr_regions;
 
-	cfi->cfiq = kmalloc(sizeof(struct cfi_ident) + num_erase_regions * 4, GFP_KERNEL);
+	cfi->cfiq = kmalloc(struct_size(cfi->cfiq, EraseRegionInfo, num_erase_regions), GFP_KERNEL);
 	if (!cfi->cfiq) {
 		//xx printk(KERN_WARNING "%s: kmalloc failed for CFI ident structure\n", map->name);
 		return 0;
-- 
2.43.0

Re: [PATCH] mtd: jedec_probe: use struct_size() helper for cfiq allocation

[Miquel Raynal]

On Mon, 22 Sep 2025 12:41:37 +0530, Rahul Kumar wrote:
> Documentation/process/deprecated.rst recommends against performing
> dynamic size calculations in the arguments of memory allocator
> functions due to the risk of overflow. Such calculations can wrap
> around and result in a smaller allocation than expected.
> 
> Replace the size calculation in cfiq allocation with struct_size()
> helper to make the code clearer and handle overflows correctly.
> 
> [...]

Applied to mtd/next, thanks!

[1/1] mtd: jedec_probe: use struct_size() helper for cfiq allocation
      commit: 527668868862e0db65efc88fe82040f1e48d4ab3

Patche(s) should be available on mtd/linux.git and will be
part of the next PR (provided that no robot complains by then).

Kind regards,
Miquèl