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Gustavo A. R. Silva c4d49196ce net: sched: cls_u32: Fix allocation size in u32_init() 
commit d61491a51f ("net/sched: cls_u32: Replace one-element array
with flexible-array member") incorrecly replaced an instance of
`sizeof(*tp_c)` with `struct_size(tp_c, hlist->ht, 1)`. This results
in a an over-allocation of 8 bytes.

This change is wrong because `hlist` in `struct tc_u_common` is a
pointer:

net/sched/cls_u32.c:
struct tc_u_common {
        struct tc_u_hnode __rcu *hlist;
        void                    *ptr;
        int                     refcnt;
        struct idr              handle_idr;
        struct hlist_node       hnode;
        long                    knodes;
};

So, the use of `struct_size()` makes no sense: we don't need to allocate
any extra space for a flexible-array member. `sizeof(*tp_c)` is just fine.

So, `struct_size(tp_c, hlist->ht, 1)` translates to:

sizeof(*tp_c) + sizeof(tp_c->hlist->ht) ==
sizeof(struct tc_u_common) + sizeof(struct tc_u_knode *) ==
						144 + 8  == 0x98 (byes)
						     ^^^
						      |
						unnecessary extra
						allocation size

$ pahole -C tc_u_common net/sched/cls_u32.o
struct tc_u_common {
	struct tc_u_hnode *        hlist;                /*     0     8 */
	void *                     ptr;                  /*     8     8 */
	int                        refcnt;               /*    16     4 */

	/* XXX 4 bytes hole, try to pack */

	struct idr                 handle_idr;           /*    24    96 */
	/* --- cacheline 1 boundary (64 bytes) was 56 bytes ago --- */
	struct hlist_node          hnode;                /*   120    16 */
	/* --- cacheline 2 boundary (128 bytes) was 8 bytes ago --- */
	long int                   knodes;               /*   136     8 */

	/* size: 144, cachelines: 3, members: 6 */
	/* sum members: 140, holes: 1, sum holes: 4 */
	/* last cacheline: 16 bytes */
};

And with `sizeof(*tp_c)`, we have:

	sizeof(*tp_c) == sizeof(struct tc_u_common) == 144 == 0x90 (bytes)

which is the correct and original allocation size.

Fix this issue by replacing `struct_size(tp_c, hlist->ht, 1)` with
`sizeof(*tp_c)`, and avoid allocating 8 too many bytes.

The following difference in binary output is expected and reflects the
desired change:

| net/sched/cls_u32.o
| @@ -6148,7 +6148,7 @@
| include/linux/slab.h:599
|     2cf5:      mov    0x0(%rip),%rdi        # 2cfc <u32_init+0xfc>
|                        2cf8: R_X86_64_PC32     kmalloc_caches+0xc
|-    2cfc:      mov    $0x98,%edx
|+    2cfc:      mov    $0x90,%edx

Reported-by: Alejandro Colomar <alx@kernel.org>
Closes: https://lore.kernel.org/lkml/09b4a2ce-da74-3a19-6961-67883f634d98@kernel.org/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2023-10-06 11:43:05 +01:00
arch Including fixes from Bluetooth, netfilter, BPF and WiFi. 2023-10-05 11:29:21 -07:00
block block: fix kernel-doc for disk_force_media_change() 2023-09-26 00:43:34 -06:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: sm2 - Fix crash caused by uninitialized context 2023-09-20 13:10:10 +08:00
Documentation Couple of small fixes, including: 2023-10-05 11:03:20 -07:00
drivers net: dsa: qca8k: fix potential MDIO bus conflict when accessing internal PHYs via management frames 2023-10-06 11:41:52 +01:00
fs overlayfs fixes for 6.6-rc5 2023-10-05 10:56:18 -07:00
include Including fixes from Bluetooth, netfilter, BPF and WiFi. 2023-10-05 11:29:21 -07:00
init workqueue: Changes for v6.6 2023-09-01 16:06:32 -07:00
io_uring io_uring/fs: remove sqe->rw_flags checking from LINKAT 2023-09-29 03:07:09 -06:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel Including fixes from Bluetooth, netfilter, BPF and WiFi. 2023-10-05 11:29:21 -07:00
lib maple_tree: add MAS_UNDERFLOW and MAS_OVERFLOW states 2023-09-29 17:20:46 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm Fourteen hotfixes, eleven of which are cc:stable. The remainder pertain 2023-10-01 13:33:25 -07:00
net net: sched: cls_u32: Fix allocation size in u32_init() 2023-10-06 11:43:05 +01:00
rust Documentation work keeps chugging along; stuff for 6.6 includes: 2023-08-30 20:05:42 -07:00
samples VFIO updates for v6.6-rc1 2023-08-30 20:36:01 -07:00
scripts kbuild: remove stale code for 'source' symlink in packaging scripts 2023-10-01 23:06:06 +09:00
security ima: rework CONFIG_IMA dependency block 2023-09-27 11:52:12 -04:00
sound ASoC: Fixes for v6.6 2023-09-20 15:02:16 +02:00
tools Including fixes from Bluetooth, netfilter, BPF and WiFi. 2023-10-05 11:29:21 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap MAINTAINERS: update Matthieu's email address 2023-10-05 09:34:32 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Including fixes from Bluetooth, netfilter, BPF and WiFi. 2023-10-05 11:29:21 -07:00
Makefile Linux 6.6-rc4 2023-10-01 14:15:13 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.