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Filename Latest commit message Latest commit date
Jacob Keller 738066cdd0 drm/nouveau/bl: increase buffer size to avoid truncate warning
[ Upstream commit 61b2b3737499f1fb361a54a16828db24a8345e85 ]

The nouveau_get_backlight_name() function generates a unique name for the
backlight interface, appending an id from 1 to 99 for all backlight devices
after the first.

GCC 15 (and likely other compilers) produce the following
-Wformat-truncation warning:

nouveau_backlight.c: In function ‘nouveau_backlight_init’:
nouveau_backlight.c:56:69: error: ‘%d’ directive output may be truncated writing between 1 and 10 bytes into a region of size 3 [-Werror=format-truncation=]
   56 |                 snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
      |                                                                     ^~
In function ‘nouveau_get_backlight_name’,
    inlined from ‘nouveau_backlight_init’ at nouveau_backlight.c:351:7:
nouveau_backlight.c:56:56: note: directive argument in the range [1, 2147483647]
   56 |                 snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
      |                                                        ^~~~~~~~~~~~~~~~
nouveau_backlight.c:56:17: note: ‘snprintf’ output between 14 and 23 bytes into a destination of size 15
   56 |                 snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The warning started appearing after commit ab244be47a8f ("drm/nouveau:
Fix a potential theorical leak in nouveau_get_backlight_name()") This fix
for the ida usage removed the explicit value check for ids larger than 99.
The compiler is unable to intuit that the ida_alloc_max() limits the
returned value range between 0 and 99.

Because the compiler can no longer infer that the number ranges from 0 to
99, it thinks that it could use as many as 11 digits (10 + the potential -
sign for negative numbers).

The warning has gone unfixed for some time, with at least one kernel test
robot report. The code breaks W=1 builds, which is especially frustrating
with the introduction of CONFIG_WERROR.

The string is stored temporarily on the stack and then copied into the
device name. Its not a big deal to use 11 more bytes of stack rounding out
to an even 24 bytes. Increase BL_NAME_SIZE to 24 to avoid the truncation
warning. This fixes the W=1 builds that include this driver.

Compile tested only.

Fixes: ab244be47a8f ("drm/nouveau: Fix a potential theorical leak in nouveau_get_backlight_name()")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202312050324.0kv4PnfZ-lkp@intel.com/
Suggested-by: Timur Tabi <ttabi@nvidia.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20250610-jk-nouveua-drm-bl-snprintf-fix-v2-1-7fdd4b84b48e@intel.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-06-27 11:02:57 +01:00
arch Revert "x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2" on v6.6 and older 2025-06-27 11:02:56 +01:00
block block: fix 'kmem_cache of name 'bio-108' already exists' 2025-04-10 14:29:37 +02:00
certs
crypto crypto: algif_hash - fix double free in hash_accept 2025-06-04 14:32:35 +02:00
Documentation Revert "x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2" on v6.6 and older 2025-06-27 11:02:56 +01:00
drivers drm/nouveau/bl: increase buffer size to avoid truncate warning 2025-06-27 11:02:57 +01:00
fs jffs2: check jffs2_prealloc_raw_node_refs() result in few other places 2025-06-27 11:02:56 +01:00
include erofs: remove unused trace event erofs_destroy_inode 2025-06-27 11:02:57 +01:00
init sched/isolation: Make CONFIG_CPU_ISOLATION depend on CONFIG_SMP 2025-05-02 07:39:28 +02:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:02:52 +01:00
kernel ftrace: Fix UAF when lookup kallsym after ftrace disabled 2025-06-27 11:02:52 +01:00
lib dql: Fix dql->limit value when reset. 2025-06-04 14:32:30 +02:00
LICENSES
mm mm: fix ratelimit_pages update error in dirty_ratio_handler() 2025-06-27 11:02:52 +01:00
net atm: Revert atm_account_tx() if copy_from_iter_full() fails. 2025-06-27 11:02:56 +01:00
samples samples/bpf: Fix a resource leak 2024-12-14 19:44:50 +01:00
scripts kbuild: fix argument parsing in scripts/config 2025-06-04 14:32:31 +02:00
security selinux: fix selinux_xfrm_alloc_user() to set correct ctx_len 2025-06-27 11:02:56 +01:00
sound ALSA: hda/realtek: enable headset mic on Latitude 5420 Rugged 2025-06-27 11:02:56 +01:00
tools perf record: Fix incorrect --user-regs comments 2025-06-27 11:02:48 +01:00
usr
virt KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status 2024-12-19 18:05:04 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS platform: Add Surface platform directory 2025-06-27 11:02:56 +01:00
Makefile Linux 5.4.294 2025-06-04 14:32:37 +02:00
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
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    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.