Re: [PATCH V1] nvmem: core: fix memory abort in cleanup path

[Bitan Biswas]

Hi Thierry,

On 1/2/20 4:44 AM, Thierry Reding wrote:
> On Sat, Dec 28, 2019 at 08:02:42PM -0800, Bitan Biswas wrote:
> > nvmem_cell_info_to_nvmem_cell implementation has static
> > allocation of name. nvmem_add_cells_from_of() call may
> > return error and kfree name results in memory abort. Use
> > kasprintf() instead of assigning pointer and prevent kfree crash.
> >
> > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> > index 9f1ee9c..0fc66e1 100644
> > --- a/drivers/nvmem/core.c
> > +++ b/drivers/nvmem/core.c
> > @@ -110,7 +110,7 @@ static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
> >   	cell->nvmem = nvmem;
> >   	cell->offset = info->offset;
> >   	cell->bytes = info->bytes;
> > -	cell->name = info->name;
> > +	cell->name = kasprintf(GFP_KERNEL, "%s", info->name);

> kstrdup() seems more appropriate here.
Thanks. I shall update the patch as suggested.

> A slightly more efficient way to do this would be to use a combination
> of kstrdup_const() and kfree_const(), which would allow read-only
> strings to be replicated by simple assignment rather than duplication.
> Note that in that case you'd need to carefully replace all kfree() calls
> on cell->name by a kfree_const() to ensure they do the right thing.
kfree(cell->name) is also called for allocations in function 
nvmem_add_cells_from_of() through below call
kasprintf(GFP_KERNEL, "%pOFn", child);

My understanding is kfree_const may not work for above allocation.



-regards,
 Bitan