* [PATCH v2] bcachefs: Prefer struct_size over open coded arithmetic
@ 2024-03-10 11:02 Erick Archer
2024-03-10 19:41 ` Kent Overstreet
0 siblings, 1 reply; 2+ messages in thread
From: Erick Archer @ 2024-03-10 11:02 UTC (permalink / raw
To: Kent Overstreet, Brian Foster, Gustavo A. R. Silva, Kees Cook
Cc: Erick Archer, linux-bcachefs, linux-kernel, linux-hardening
This is an effort to get rid of all multiplications from allocation
functions in order to prevent integer overflows [1][2].
As the "op" variable is a pointer to "struct promote_op" and this
structure ends in a flexible array:
struct promote_op {
[...]
struct bio_vec bi_inline_vecs[];
};
and the "t" variable is a pointer to "struct journal_seq_blacklist_table"
and this structure also ends in a flexible array:
struct journal_seq_blacklist_table {
[...]
struct journal_seq_blacklist_table_entry {
u64 start;
u64 end;
bool dirty;
} entries[];
};
the preferred way in the kernel is to use the struct_size() helper to
do the arithmetic instead of the argument "size + size * count" in the
kzalloc() functions.
This way, the code is more readable and safer.
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
Link: https://github.com/KSPP/linux/issues/160 [2]
Signed-off-by: Erick Archer <erick.archer@gmx.com>
---
Changes in v2:
- Merge the two patches in one single patch (Kent Overstreet).
Previous versions:
v1 -> https://lore.kernel.org/linux-hardening/20240224145924.7468-1-erick.archer@gmx.com/
v1 -> https://lore.kernel.org/linux-hardening/20240224151658.8272-1-erick.archer@gmx.com/
---
fs/bcachefs/io_read.c | 2 +-
fs/bcachefs/journal_seq_blacklist.c | 3 +--
2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/fs/bcachefs/io_read.c b/fs/bcachefs/io_read.c
index dce136cd2271..01beab55c6b3 100644
--- a/fs/bcachefs/io_read.c
+++ b/fs/bcachefs/io_read.c
@@ -174,7 +174,7 @@ static struct promote_op *__promote_alloc(struct btree_trans *trans,
if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_promote))
return ERR_PTR(-BCH_ERR_nopromote_no_writes);
- op = kzalloc(sizeof(*op) + sizeof(struct bio_vec) * pages, GFP_KERNEL);
+ op = kzalloc(struct_size(op, bi_inline_vecs, pages), GFP_KERNEL);
if (!op) {
ret = -BCH_ERR_nopromote_enomem;
goto err;
diff --git a/fs/bcachefs/journal_seq_blacklist.c b/fs/bcachefs/journal_seq_blacklist.c
index 024c9b1b323f..2c2490aa15fe 100644
--- a/fs/bcachefs/journal_seq_blacklist.c
+++ b/fs/bcachefs/journal_seq_blacklist.c
@@ -165,8 +165,7 @@ int bch2_blacklist_table_initialize(struct bch_fs *c)
if (!bl)
return 0;
- t = kzalloc(sizeof(*t) + sizeof(t->entries[0]) * nr,
- GFP_KERNEL);
+ t = kzalloc(struct_size(t, entries, nr), GFP_KERNEL);
if (!t)
return -BCH_ERR_ENOMEM_blacklist_table_init;
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] bcachefs: Prefer struct_size over open coded arithmetic
2024-03-10 11:02 [PATCH v2] bcachefs: Prefer struct_size over open coded arithmetic Erick Archer
@ 2024-03-10 19:41 ` Kent Overstreet
0 siblings, 0 replies; 2+ messages in thread
From: Kent Overstreet @ 2024-03-10 19:41 UTC (permalink / raw
To: Erick Archer
Cc: Brian Foster, Gustavo A. R. Silva, Kees Cook, linux-bcachefs,
linux-kernel, linux-hardening
On Sun, Mar 10, 2024 at 12:02:26PM +0100, Erick Archer wrote:
> This is an effort to get rid of all multiplications from allocation
> functions in order to prevent integer overflows [1][2].
>
> As the "op" variable is a pointer to "struct promote_op" and this
> structure ends in a flexible array:
>
> struct promote_op {
> [...]
> struct bio_vec bi_inline_vecs[];
> };
>
> and the "t" variable is a pointer to "struct journal_seq_blacklist_table"
> and this structure also ends in a flexible array:
>
> struct journal_seq_blacklist_table {
> [...]
> struct journal_seq_blacklist_table_entry {
> u64 start;
> u64 end;
> bool dirty;
> } entries[];
> };
>
> the preferred way in the kernel is to use the struct_size() helper to
> do the arithmetic instead of the argument "size + size * count" in the
> kzalloc() functions.
>
> This way, the code is more readable and safer.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Link: https://github.com/KSPP/linux/issues/160 [2]
> Signed-off-by: Erick Archer <erick.archer@gmx.com>
applied
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