When compiling the kernel in my environment (with gcc version gcc
10.3.1), I encountered the following compilation check error:
In function ‘check_copy_size’,
inlined from ‘copy_to_user’ at ./include/linux/uaccess.h:210:7,
inlined from ‘mlx4_init_user_cqes’ at drivers/net/ethernet/mellanox/mlx4/cq.c:317:9:
./include/linux/thread_info.h:244:4: error: call to ‘__bad_copy_from’ declared with attribute error: copy source size is too small
244 | __bad_copy_from();
mlx4_init_user_cqes() checks the size of the buf before copying data,
ensuring that there will be no out-of-bounds copying, so this should be
a false positive. I searched the git commit history and found that the
commit 75da0eba0a47 ("rapidio: avoid bogus __alloc_size warning") fixed
a similar issue, where the compiler encountered an error when expanding
the arguments of check_copy_size(). Saving the result of array_size()
to a temporary variable and using this variable as the argument of
copy_to_user() can avoid this gcc warning.
Additionally, I tested older (9.4.0) and newer (10.3.5) versions and did
not encounter the same problem, so this should be a bug in a specific
intermediate version.
Signed-off-by: Li Huafei <lihuafei1@xxxxxxxxxx>
---
drivers/net/ethernet/mellanox/mlx4/cq.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx4/cq.c b/drivers/net/ethernet/mellanox/mlx4/cq.c
index e130e7259275..5169c7a4097b 100644
--- a/drivers/net/ethernet/mellanox/mlx4/cq.c
+++ b/drivers/net/ethernet/mellanox/mlx4/cq.c
@@ -293,6 +293,7 @@ static int mlx4_init_user_cqes(void *buf, int entries, int cqe_size)
void *init_ents;
int err = 0;
int i;
+ size_t size = array_size(entries, cqe_size);
init_ents = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!init_ents)
@@ -314,9 +315,7 @@ static int mlx4_init_user_cqes(void *buf, int entries, int cqe_size)
buf += PAGE_SIZE;
}
} else {
- err = copy_to_user((void __user *)buf, init_ents,
- array_size(entries, cqe_size)) ?
- -EFAULT : 0;
+ err = copy_to_user((void __user *)buf, init_ents, size) ? -EFAULT : 0;
}
out:
--
2.25.1
