* [PATCH] ntfs3: harden against integer overflows
@ 2022-09-12 15:08 Dan Carpenter
2022-09-30 16:07 ` Konstantin Komarov
0 siblings, 1 reply; 2+ messages in thread
From: Dan Carpenter @ 2022-09-12 15:08 UTC (permalink / raw)
To: Konstantin Komarov; +Cc: ntfs3, kernel-janitors
Smatch complains that the "add_bytes" is not to be trusted. Use
size_add() to prevent an integer overflow.
Fixes: be71b5cba2e6 ("fs/ntfs3: Add attrib operations")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
The add_bytes variable comes from:
add = ALIGN(struct_size(ea_all, name, 1 + name_len + val_size), 4);
This is problematic and has inspired a new static checker warning:
fs/ntfs3/xattr.c:26 unpacked_ea_size() warn: using integer overflow function 'size_add()' for math
fs/ntfs3/xattr.c:290 ntfs_set_ea() warn: using integer overflow function 'size_add()' for math
The issue is that the struct_size() has an integer overflow and we call
ALIGN() on it, then "add" becomes zero. Is there a bounds check that
we could use here?
add = struct_size(ea_all, name, 1 + name_len + val_size);
if (add > SOMETHING_MAX)
return -EINVAL;
Otherwise the limit would have to be if (add > ULONG_MAX - 3) { which
is ugly.
fs/ntfs3/xattr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
index 7de8718c68a9..ea582b4fe1d9 100644
--- a/fs/ntfs3/xattr.c
+++ b/fs/ntfs3/xattr.c
@@ -107,7 +107,7 @@ static int ntfs_read_ea(struct ntfs_inode *ni, struct EA_FULL **ea,
return -EFBIG;
/* Allocate memory for packed Ea. */
- ea_p = kmalloc(size + add_bytes, GFP_NOFS);
+ ea_p = kmalloc(size_add(size, add_bytes), GFP_NOFS);
if (!ea_p)
return -ENOMEM;
--
2.35.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ntfs3: harden against integer overflows
2022-09-12 15:08 [PATCH] ntfs3: harden against integer overflows Dan Carpenter
@ 2022-09-30 16:07 ` Konstantin Komarov
0 siblings, 0 replies; 2+ messages in thread
From: Konstantin Komarov @ 2022-09-30 16:07 UTC (permalink / raw)
To: Dan Carpenter; +Cc: ntfs3, kernel-janitors
On 9/12/22 18:08, Dan Carpenter wrote:
> Smatch complains that the "add_bytes" is not to be trusted. Use
> size_add() to prevent an integer overflow.
>
> Fixes: be71b5cba2e6 ("fs/ntfs3: Add attrib operations")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> The add_bytes variable comes from:
>
> add = ALIGN(struct_size(ea_all, name, 1 + name_len + val_size), 4);
>
> This is problematic and has inspired a new static checker warning:
>
> fs/ntfs3/xattr.c:26 unpacked_ea_size() warn: using integer overflow function 'size_add()' for math
> fs/ntfs3/xattr.c:290 ntfs_set_ea() warn: using integer overflow function 'size_add()' for math
>
> The issue is that the struct_size() has an integer overflow and we call
> ALIGN() on it, then "add" becomes zero. Is there a bounds check that
> we could use here?
>
> add = struct_size(ea_all, name, 1 + name_len + val_size);
> if (add > SOMETHING_MAX)
> return -EINVAL;
>
> Otherwise the limit would have to be if (add > ULONG_MAX - 3) { which
> is ugly.
>
> fs/ntfs3/xattr.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
> index 7de8718c68a9..ea582b4fe1d9 100644
> --- a/fs/ntfs3/xattr.c
> +++ b/fs/ntfs3/xattr.c
> @@ -107,7 +107,7 @@ static int ntfs_read_ea(struct ntfs_inode *ni, struct EA_FULL **ea,
> return -EFBIG;
>
> /* Allocate memory for packed Ea. */
> - ea_p = kmalloc(size + add_bytes, GFP_NOFS);
> + ea_p = kmalloc(size_add(size, add_bytes), GFP_NOFS);
> if (!ea_p)
> return -ENOMEM;
>
Applied, thanks!
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2022-09-30 16:07 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-09-12 15:08 [PATCH] ntfs3: harden against integer overflows Dan Carpenter
2022-09-30 16:07 ` Konstantin Komarov
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).