From a7508c7959ff8d037327d377ed21a9c0eabe4674 Mon Sep 17 00:00:00 2001 From: Muhammad Bilal Date: Wed, 12 Aug 2026 16:18:22 +0500 Subject: [PATCH] platform/x86: hp-bioscfg: fix heap OOB read in sk_store() and kek_store() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit sk_store() and kek_store() strip a trailing newline from the sysfs write before allocating the key buffer: length = count; if (buf[length - 1] == '\n') length--; bioscfg_drv.spm_data.signing_key = kmemdup(buf, length, GFP_KERNEL); but then pass the original "count" (not "length") as the copy size to hp_wmi_perform_query(), which memcpy()s that many bytes out of the "length"-sized allocation, reading one byte past it whenever the write ends in a newline, the normal case for a shell "echo" into sysfs. KASAN confirms this directly: BUG: KASAN: slab-out-of-bounds in hp_wmi_perform_query+0x1e9/0x460 [hp_bioscfg] Read of size 28 at addr ffff88813c8e2b80 by task python3/16022 ... sk_store+0xa7/0x240 [hp_bioscfg] kernfs_fop_write_iter+0x3e1/0x5d0 ... The buggy address is located 0 bytes inside of allocated 27-byte region [ffff88813c8e2b80, ffff88813c8e2b9b) Reproduced identically for kek_store, and at multiple write sizes (28, 57, 201 bytes), each time reading exactly one byte past a kmemdup() allocation one byte smaller than the write. Fix by passing "length" instead of "count" to hp_wmi_perform_query() in both functions. Fixes: b2715aa2e135 ("platform/x86: hp-bioscfg: spmobj-attributes") Cc: stable@vger.kernel.org Signed-off-by: Muhammad Bilal Link: https://patch.msgid.link/20260812111829.172273-3-meatuni001@gmail.com Reviewed-by: Ilpo Järvinen Signed-off-by: Ilpo Järvinen --- drivers/platform/x86/hp/hp-bioscfg/spmobj-attributes.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/platform/x86/hp/hp-bioscfg/spmobj-attributes.c b/drivers/platform/x86/hp/hp-bioscfg/spmobj-attributes.c index 2b00a14792e9..4d94e48c1a4c 100644 --- a/drivers/platform/x86/hp/hp-bioscfg/spmobj-attributes.c +++ b/drivers/platform/x86/hp/hp-bioscfg/spmobj-attributes.c @@ -238,7 +238,7 @@ static ssize_t sk_store(struct kobject *kobj, ret = hp_wmi_perform_query(HPWMI_SECUREPLATFORM_SET_SK, HPWMI_SECUREPLATFORM, (void *)bioscfg_drv.spm_data.signing_key, - count, 0); + length, 0); if (!ret) { bioscfg_drv.spm_data.mechanism = SIGNING_KEY; @@ -274,7 +274,7 @@ static ssize_t kek_store(struct kobject *kobj, ret = hp_wmi_perform_query(HPWMI_SECUREPLATFORM_SET_KEK, HPWMI_SECUREPLATFORM, (void *)bioscfg_drv.spm_data.endorsement_key, - count, 0); + length, 0); if (!ret) { bioscfg_drv.spm_data.mechanism = ENDORSEMENT_KEY;