| Message ID | 20210919094539.30589-1-len.baker@gmx.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | aio: Prefer struct_size over open coded arithmetic | expand |
On 9/19/21 04:45, Len Baker wrote: > As noted in the "Deprecated Interfaces, Language Features, Attributes, > and Conventions" documentation [1], size calculations (especially > multiplication) should not be performed in memory allocator (or similar) > function arguments due to the risk of them overflowing. This could lead > to values wrapping around and a smaller allocation being made than the > caller was expecting. Using those allocations could lead to linear > overflows of heap memory and other misbehaviors. > > So, use the struct_size() helper to do the arithmetic instead of the > argument "size + size * count" in the kzalloc() function. > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > Signed-off-by: Len Baker <len.baker@gmx.com> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Thanks -- Gustavo > --- > fs/aio.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/fs/aio.c b/fs/aio.c > index 51b08ab01dff..c2978c0b872c 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -659,8 +659,7 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm) > new_nr = (table ? table->nr : 1) * 4; > spin_unlock(&mm->ioctx_lock); > > - table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) * > - new_nr, GFP_KERNEL); > + table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL); > if (!table) > return -ENOMEM; > > -- > 2.25.1 >
On Mon, Sep 20, 2021 at 07:11:17PM -0500, Gustavo A. R. Silva wrote: > > > On 9/19/21 04:45, Len Baker wrote: > > As noted in the "Deprecated Interfaces, Language Features, Attributes, > > and Conventions" documentation [1], size calculations (especially > > multiplication) should not be performed in memory allocator (or similar) > > function arguments due to the risk of them overflowing. This could lead > > to values wrapping around and a smaller allocation being made than the > > caller was expecting. Using those allocations could lead to linear > > overflows of heap memory and other misbehaviors. > > > > So, use the struct_size() helper to do the arithmetic instead of the > > argument "size + size * count" in the kzalloc() function. > > > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > > > Signed-off-by: Len Baker <len.baker@gmx.com> > > Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> I'm taking this in my -next tree. Thanks, Len. -- Gustavo
diff --git a/fs/aio.c b/fs/aio.c index 51b08ab01dff..c2978c0b872c 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -659,8 +659,7 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm) new_nr = (table ? table->nr : 1) * 4; spin_unlock(&mm->ioctx_lock); - table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) * - new_nr, GFP_KERNEL); + table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL); if (!table) return -ENOMEM;
As noted in the "Deprecated Interfaces, Language Features, Attributes, and Conventions" documentation [1], size calculations (especially multiplication) should not be performed in memory allocator (or similar) function arguments due to the risk of them overflowing. This could lead to values wrapping around and a smaller allocation being made than the caller was expecting. Using those allocations could lead to linear overflows of heap memory and other misbehaviors. So, use the struct_size() helper to do the arithmetic instead of the argument "size + size * count" in the kzalloc() function. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments Signed-off-by: Len Baker <len.baker@gmx.com> --- fs/aio.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) -- 2.25.1