From ced45be0073a8a31b30b4a7f68cd3a15734515de Mon Sep 17 00:00:00 2001 From: Anirudh Prasad Date: Sat, 15 Aug 2026 01:36:23 +0530 Subject: [PATCH] ACPI: pfr_update: fix stack buffer overflow in query_capability() query_capability() copies four ACPI buffer objects returned by the firmware _DSM into fixed-size u8[16] fields in struct pfru_update_cap_info using memcpy with the firmware-supplied length: memcpy(&cap_hdr->code_type, elements[CAP_CODE_TYPE_IDX].buffer.pointer, elements[CAP_CODE_TYPE_IDX].buffer.length); The same pattern repeats for drv_type, platform_id, and oem_id. If the firmware returns buffer.length > 16 for any of these fields, memcpy writes past the destination array. struct pfru_update_cap_info is stack-allocated in pfru_ioctl(). Confirmed with KASAN on 7.2-rc6: three stack-out-of-bounds reports are generated when a DSM returns 64-byte buffers, with writes reaching 44 bytes past the end of cap_hdr's [64, 156) frame window into adjacent stack redzones. Introduce a helper pointer to out_obj->package.elements and use it to validate each buffer length against its destination field size before copying, returning -EINVAL if the firmware supplies an oversized buffer. Fixes: 0db89fa243e5 ("ACPI: Introduce Platform Firmware Runtime Update device driver") Cc: All applicable Signed-off-by: Anirudh Prasad Link: https://patch.msgid.link/1a001e1fee9.637da6dc3533246.238498880682901704@a0rg.com Signed-off-by: Rafael J. Wysocki --- drivers/acpi/pfr_update.c | 45 +++++++++++++++++++++------------------ 1 file changed, 24 insertions(+), 21 deletions(-) diff --git a/drivers/acpi/pfr_update.c b/drivers/acpi/pfr_update.c index 6283105bb0e8..9afd2c52fdbd 100644 --- a/drivers/acpi/pfr_update.c +++ b/drivers/acpi/pfr_update.c @@ -120,7 +120,7 @@ static int query_capability(struct pfru_update_cap_info *cap_hdr, struct pfru_device *pfru_dev) { acpi_handle handle = ACPI_HANDLE(pfru_dev->parent_dev); - union acpi_object *out_obj; + union acpi_object *out_obj, *elem; int ret = -EINVAL; out_obj = acpi_evaluate_dsm_typed(handle, &pfru_guid, @@ -150,7 +150,9 @@ static int query_capability(struct pfru_update_cap_info *cap_hdr, goto free_acpi_buffer; } - cap_hdr->status = out_obj->package.elements[CAP_STATUS_IDX].integer.value; + elem = out_obj->package.elements; + + cap_hdr->status = elem[CAP_STATUS_IDX].integer.value; if (cap_hdr->status != DSM_SUCCEED) { ret = -EBUSY; dev_dbg(pfru_dev->parent_dev, "Query cap Error Status:%d\n", @@ -158,29 +160,30 @@ static int query_capability(struct pfru_update_cap_info *cap_hdr, goto free_acpi_buffer; } - cap_hdr->update_cap = out_obj->package.elements[CAP_UPDATE_IDX].integer.value; + if (elem[CAP_CODE_TYPE_IDX].buffer.length > sizeof(cap_hdr->code_type) || + elem[CAP_DRV_TYPE_IDX].buffer.length > sizeof(cap_hdr->drv_type) || + elem[CAP_PLAT_ID_IDX].buffer.length > sizeof(cap_hdr->platform_id) || + elem[CAP_OEM_ID_IDX].buffer.length > sizeof(cap_hdr->oem_id)) + goto free_acpi_buffer; + + cap_hdr->update_cap = elem[CAP_UPDATE_IDX].integer.value; memcpy(&cap_hdr->code_type, - out_obj->package.elements[CAP_CODE_TYPE_IDX].buffer.pointer, - out_obj->package.elements[CAP_CODE_TYPE_IDX].buffer.length); - cap_hdr->fw_version = - out_obj->package.elements[CAP_FW_VER_IDX].integer.value; - cap_hdr->code_rt_version = - out_obj->package.elements[CAP_CODE_RT_VER_IDX].integer.value; + elem[CAP_CODE_TYPE_IDX].buffer.pointer, + elem[CAP_CODE_TYPE_IDX].buffer.length); + cap_hdr->fw_version = elem[CAP_FW_VER_IDX].integer.value; + cap_hdr->code_rt_version = elem[CAP_CODE_RT_VER_IDX].integer.value; memcpy(&cap_hdr->drv_type, - out_obj->package.elements[CAP_DRV_TYPE_IDX].buffer.pointer, - out_obj->package.elements[CAP_DRV_TYPE_IDX].buffer.length); - cap_hdr->drv_rt_version = - out_obj->package.elements[CAP_DRV_RT_VER_IDX].integer.value; - cap_hdr->drv_svn = - out_obj->package.elements[CAP_DRV_SVN_IDX].integer.value; + elem[CAP_DRV_TYPE_IDX].buffer.pointer, + elem[CAP_DRV_TYPE_IDX].buffer.length); + cap_hdr->drv_rt_version = elem[CAP_DRV_RT_VER_IDX].integer.value; + cap_hdr->drv_svn = elem[CAP_DRV_SVN_IDX].integer.value; memcpy(&cap_hdr->platform_id, - out_obj->package.elements[CAP_PLAT_ID_IDX].buffer.pointer, - out_obj->package.elements[CAP_PLAT_ID_IDX].buffer.length); + elem[CAP_PLAT_ID_IDX].buffer.pointer, + elem[CAP_PLAT_ID_IDX].buffer.length); memcpy(&cap_hdr->oem_id, - out_obj->package.elements[CAP_OEM_ID_IDX].buffer.pointer, - out_obj->package.elements[CAP_OEM_ID_IDX].buffer.length); - cap_hdr->oem_info_len = - out_obj->package.elements[CAP_OEM_INFO_IDX].buffer.length; + elem[CAP_OEM_ID_IDX].buffer.pointer, + elem[CAP_OEM_ID_IDX].buffer.length); + cap_hdr->oem_info_len = elem[CAP_OEM_INFO_IDX].buffer.length; ret = 0;