fw_cfg_read_blob() may fail, but does not return error. This may lead to undefined behaviours, such as a memcmp(sig, "QEMU") on uninitilized memory. Return an error if ACPI locking failed. Also, the following DMA read/write extension will add more error paths that should be handled appropriately.
Signed-off-by: Marc-André Lureau <[email protected]> --- drivers/firmware/qemu_fw_cfg.c | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c index f6f90bef604c..5e6e5ac71dab 100644 --- a/drivers/firmware/qemu_fw_cfg.c +++ b/drivers/firmware/qemu_fw_cfg.c @@ -59,8 +59,8 @@ static void fw_cfg_sel_endianness(u16 key) } /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */ -static void fw_cfg_read_blob(u16 key, - void *buf, loff_t pos, size_t count) +static ssize_t fw_cfg_read_blob(u16 key, + void *buf, loff_t pos, size_t count) { u32 glk = -1U; acpi_status status; @@ -73,7 +73,7 @@ static void fw_cfg_read_blob(u16 key, /* Should never get here */ WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n"); memset(buf, 0, count); - return; + return -EINVAL; } mutex_lock(&fw_cfg_dev_lock); @@ -84,6 +84,7 @@ static void fw_cfg_read_blob(u16 key, mutex_unlock(&fw_cfg_dev_lock); acpi_release_global_lock(glk); + return count; } /* clean up fw_cfg device i/o */ @@ -165,8 +166,9 @@ static int fw_cfg_do_platform_probe(struct platform_device *pdev) } /* verify fw_cfg device signature */ - fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE); - if (memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) { + if (fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, + 0, FW_CFG_SIG_SIZE) < 0 || + memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) { fw_cfg_io_cleanup(); return -ENODEV; } @@ -326,8 +328,7 @@ static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj, if (count > entry->size - pos) count = entry->size - pos; - fw_cfg_read_blob(entry->select, buf, pos, count); - return count; + return fw_cfg_read_blob(entry->select, buf, pos, count); } static struct bin_attribute fw_cfg_sysfs_attr_raw = { @@ -483,7 +484,11 @@ static int fw_cfg_register_dir_entries(void) struct fw_cfg_file *dir; size_t dir_size; - fw_cfg_read_blob(FW_CFG_FILE_DIR, &files_count, 0, sizeof(files_count)); + ret = fw_cfg_read_blob(FW_CFG_FILE_DIR, &files_count, + 0, sizeof(files_count)); + if (ret < 0) + return ret; + count = be32_to_cpu(files_count); dir_size = count * sizeof(struct fw_cfg_file); @@ -491,7 +496,10 @@ static int fw_cfg_register_dir_entries(void) if (!dir) return -ENOMEM; - fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(files_count), dir_size); + ret = fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, + sizeof(files_count), dir_size); + if (ret < 0) + goto end; for (i = 0; i < count; i++) { ret = fw_cfg_register_file(&dir[i]); @@ -499,6 +507,7 @@ static int fw_cfg_register_dir_entries(void) break; } +end: kfree(dir); return ret; } @@ -539,7 +548,10 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev) goto err_probe; /* get revision number, add matching top-level attribute */ - fw_cfg_read_blob(FW_CFG_ID, &rev, 0, sizeof(rev)); + err = fw_cfg_read_blob(FW_CFG_ID, &rev, 0, sizeof(rev)); + if (err < 0) + goto err_probe; + fw_cfg_rev = le32_to_cpu(rev); err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr); if (err) -- 2.16.1.73.g5832b7e9f2
