bootcmdline_append() passes "max" (the maximum length of the source string "s") as the destination buffer size argument to strlcat(). Because strlcat() expects the total size of the destination buffer (COMMAND_LINE_SIZE), it fails to append anything whenever "max" is smaller than the current length of boot_command_line, and could overflow boot_command_line if "max" exceeds COMMAND_LINE_SIZE. In preparation for removing the deprecated strlcat() API[1], replace the strlcat() calls with snprintf() using the "%.*s" precision specifier. This bounds the read from "s" to at most "max" bytes while properly respecting the remaining space in boot_command_line. Link: https://github.com/KSPP/linux/issues/370 [1] Cc: codemender-patching+linux@google.com Assisted-by: SecurityEngineer:Gemini2.5Pro [editor_update_file, shell_command_run, make_kernel_build_single_file, test_runner_run_kunit_test] Signed-off-by: Bill Wendling --- Cc: Russell King Cc: Huacai Chen Cc: WANG Xuerui Cc: Thomas Bogendoerfer Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: x86@kernel.org Cc: "H. Peter Anvin" Cc: Ian Abbott Cc: H Hartley Sweeten Cc: Tony Luck Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: David Airlie Cc: Simona Vetter Cc: Matthew Brost Cc: "Thomas Hellström" Cc: Rodrigo Vivi Cc: Dmitry Torokhov Cc: Matthias Schwarzott Cc: Mauro Carvalho Chehab Cc: Tony Nguyen Cc: Przemek Kitszel Cc: Andrew Lunn Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Arend van Spriel Cc: Rob Herring Cc: Saravana Kannan Cc: Krzysztof Kozlowski Cc: Sylwester Nawrocki Cc: Peter Griffin Cc: Alim Akhtar Cc: Linus Walleij Cc: Anil Gurumurthy Cc: Sudarsana Kalluru Cc: "Martin K. Petersen" Cc: Trond Myklebust Cc: Anna Schumaker Cc: Mike Marshall Cc: Martin Brandenburg Cc: Kees Cook Cc: Jiri Pirko Cc: Simon Horman Cc: Chuck Lever Cc: Jeff Layton Cc: NeilBrown Cc: Olga Kornievskaia Cc: Dai Ngo Cc: Tom Talpey Cc: Jaroslav Kysela Cc: Takashi Iwai Cc: Bill Wendling Cc: Andrew Morton Cc: "Mike Rapoport (Microsoft)" Cc: Kanglong Wang Cc: Tiezhu Yang Cc: Qiang Ma Cc: Randy Dunlap Cc: Pengpeng Hou Cc: Ard Biesheuvel Cc: Breno Leitao Cc: Thorsten Blum Cc: Harshit Mogalapalli Cc: Greg Kroah-Hartman Cc: Lyude Paul Cc: Ashutosh Desai Cc: Imre Deak Cc: Dmitry Baryshkov Cc: Johan Hovold Cc: Johannes Berg Cc: Miri Korenblit Cc: Alexander Stein Cc: Cryolitia PukNgae Cc: Jiaming Zhang Cc: Will Porter Cc: Cen Zhang Cc: "Cássio Gabriel" Cc: Rong Zhang Cc: Arun Raghavan Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: loongarch@lists.linux.dev Cc: linux-mips@vger.kernel.org Cc: linux-parisc@vger.kernel.org Cc: linux-edac@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: intel-xe@lists.freedesktop.org Cc: linux-input@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: intel-wired-lan@lists.osuosl.org Cc: netdev@vger.kernel.org Cc: linux-wireless@vger.kernel.org Cc: brcm80211@lists.linux.dev Cc: brcm80211-dev-list.pdl@broadcom.com Cc: devicetree@vger.kernel.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-gpio@vger.kernel.org Cc: linux-scsi@vger.kernel.org Cc: linux-nfs@vger.kernel.org Cc: devel@lists.orangefs.org Cc: linux-hardening@vger.kernel.org Cc: linux-sound@vger.kernel.org --- arch/mips/kernel/setup.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c index 1ae6d0c0e1d6..0d9c2137d675 100644 --- a/arch/mips/kernel/setup.c +++ b/arch/mips/kernel/setup.c @@ -518,13 +518,28 @@ static void __init check_kernel_sections_mem(void) static void __init bootcmdline_append(const char *s, size_t max) { + size_t len; + int prec; + if (!s[0] || !max) return; - if (boot_command_line[0]) - strlcat(boot_command_line, " ", COMMAND_LINE_SIZE); + len = strlen(boot_command_line); + if (len >= COMMAND_LINE_SIZE - 1) + return; - strlcat(boot_command_line, s, max); + if (len) { + if (COMMAND_LINE_SIZE - len < 3) + return; + + prec = min_t(size_t, max, COMMAND_LINE_SIZE - len - 2); + snprintf(boot_command_line + len, COMMAND_LINE_SIZE - len, " %.*s", + prec, s); + } else { + prec = min_t(size_t, max, COMMAND_LINE_SIZE - 1); + snprintf(boot_command_line, COMMAND_LINE_SIZE, "%.*s", + prec, s); + } } #ifdef CONFIG_OF_EARLY_FLATTREE -- 2.55.0.1032.g73a4cd73de-goog