From: Len Baker <len.baker@gmx.com>
To: Andrew Morton <akpm@linux-foundation.org>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
Kees Cook <keescook@chromium.org>
Cc: Len Baker <len.baker@gmx.com>, Miguel Ojeda <ojeda@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Nathan Chancellor <nathan@kernel.org>,
linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] assoc_array: Avoid open coded arithmetic in allocator arguments
Date: Sun, 19 Sep 2021 13:09:13 +0200 [thread overview]
Message-ID: <20210919110913.39386-1-len.baker@gmx.com> (raw)
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 + count * size" in the kmalloc() and kzalloc() functions.
Also, take the opportunity to refactor the memcpy() calls to use the
struct_size() and flex_array_size() helpers.
[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>
---
lib/assoc_array.c | 22 ++++++++++------------
1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/lib/assoc_array.c b/lib/assoc_array.c
index 04c98799c3ba..079c72e26493 100644
--- a/lib/assoc_array.c
+++ b/lib/assoc_array.c
@@ -741,8 +741,7 @@ static bool assoc_array_insert_into_terminal_node(struct assoc_array_edit *edit,
keylen = round_up(diff, ASSOC_ARRAY_KEY_CHUNK_SIZE);
keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT;
- new_s0 = kzalloc(sizeof(struct assoc_array_shortcut) +
- keylen * sizeof(unsigned long), GFP_KERNEL);
+ new_s0 = kzalloc(struct_size(new_s0, index_key, keylen), GFP_KERNEL);
if (!new_s0)
return false;
edit->new_meta[2] = assoc_array_shortcut_to_ptr(new_s0);
@@ -849,8 +848,8 @@ static bool assoc_array_insert_mid_shortcut(struct assoc_array_edit *edit,
keylen = round_up(diff, ASSOC_ARRAY_KEY_CHUNK_SIZE);
keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT;
- new_s0 = kzalloc(sizeof(struct assoc_array_shortcut) +
- keylen * sizeof(unsigned long), GFP_KERNEL);
+ new_s0 = kzalloc(struct_size(new_s0, index_key, keylen),
+ GFP_KERNEL);
if (!new_s0)
return false;
edit->new_meta[1] = assoc_array_shortcut_to_ptr(new_s0);
@@ -864,7 +863,7 @@ static bool assoc_array_insert_mid_shortcut(struct assoc_array_edit *edit,
new_n0->parent_slot = 0;
memcpy(new_s0->index_key, shortcut->index_key,
- keylen * sizeof(unsigned long));
+ flex_array_size(new_s0, index_key, keylen));
blank = ULONG_MAX << (diff & ASSOC_ARRAY_KEY_CHUNK_MASK);
pr_devel("blank off [%zu] %d: %lx\n", keylen - 1, diff, blank);
@@ -899,8 +898,8 @@ static bool assoc_array_insert_mid_shortcut(struct assoc_array_edit *edit,
keylen = round_up(shortcut->skip_to_level, ASSOC_ARRAY_KEY_CHUNK_SIZE);
keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT;
- new_s1 = kzalloc(sizeof(struct assoc_array_shortcut) +
- keylen * sizeof(unsigned long), GFP_KERNEL);
+ new_s1 = kzalloc(struct_size(new_s1, index_key, keylen),
+ GFP_KERNEL);
if (!new_s1)
return false;
edit->new_meta[2] = assoc_array_shortcut_to_ptr(new_s1);
@@ -913,7 +912,7 @@ static bool assoc_array_insert_mid_shortcut(struct assoc_array_edit *edit,
new_n0->slots[sc_slot] = assoc_array_shortcut_to_ptr(new_s1);
memcpy(new_s1->index_key, shortcut->index_key,
- keylen * sizeof(unsigned long));
+ flex_array_size(new_s1, index_key, keylen));
edit->set[1].ptr = &side->back_pointer;
edit->set[1].to = assoc_array_shortcut_to_ptr(new_s1);
@@ -1490,13 +1489,12 @@ int assoc_array_gc(struct assoc_array *array,
shortcut = assoc_array_ptr_to_shortcut(cursor);
keylen = round_up(shortcut->skip_to_level, ASSOC_ARRAY_KEY_CHUNK_SIZE);
keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT;
- new_s = kmalloc(sizeof(struct assoc_array_shortcut) +
- keylen * sizeof(unsigned long), GFP_KERNEL);
+ new_s = kmalloc(struct_size(new_s, index_key, keylen),
+ GFP_KERNEL);
if (!new_s)
goto enomem;
pr_devel("dup shortcut %p -> %p\n", shortcut, new_s);
- memcpy(new_s, shortcut, (sizeof(struct assoc_array_shortcut) +
- keylen * sizeof(unsigned long)));
+ memcpy(new_s, shortcut, struct_size(new_s, index_key, keylen));
new_s->back_pointer = new_parent;
new_s->parent_slot = shortcut->parent_slot;
*new_ptr_pp = new_parent = assoc_array_shortcut_to_ptr(new_s);
--
2.25.1
next reply other threads:[~2021-09-19 11:09 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-19 11:09 Len Baker [this message]
2021-09-21 18:30 ` [PATCH] assoc_array: Avoid open coded arithmetic in allocator arguments Gustavo A. R. Silva
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210919110913.39386-1-len.baker@gmx.com \
--to=len.baker@gmx.com \
--cc=akpm@linux-foundation.org \
--cc=gustavoars@kernel.org \
--cc=keescook@chromium.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=nathan@kernel.org \
--cc=ndesaulniers@google.com \
--cc=ojeda@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).