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fw_cfg: handle fw_cfg_read_blob() error

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fw_cfg_read_blob() may fail, but does not return error. This may lead
to surprising behaviours, like populating zero file entries (in
register_file() or during read). 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 <marcandre.lureau@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Marc-André Lureau 2018-02-28 16:06:10 +01:00 • committed by Michael S. Tsirkin
parent 59ecab182f
commit b1cc4097d1
1 changed files with 22 additions and 10 deletions
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30
drivers/firmware/qemu_fw_cfg.c
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@ -77,7 +77,7 @@ static void fw_cfg_sel_endianness(u16 key)
} }
/* read chunk of given fw_cfg blob (caller responsible for sanity-check) */ /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */
static void fw_cfg_read_blob(u16 key, static ssize_t fw_cfg_read_blob(u16 key,
void *buf, loff_t pos, size_t count) void *buf, loff_t pos, size_t count)
{ {
u32 glk = -1U; u32 glk = -1U;
@ -91,7 +91,7 @@ static void fw_cfg_read_blob(u16 key,
/* Should never get here */ /* Should never get here */
WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n"); WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n");
memset(buf, 0, count); memset(buf, 0, count);
return; return -EINVAL;
} }
mutex_lock(&fw_cfg_dev_lock); mutex_lock(&fw_cfg_dev_lock);
@ -102,6 +102,7 @@ static void fw_cfg_read_blob(u16 key,
mutex_unlock(&fw_cfg_dev_lock); mutex_unlock(&fw_cfg_dev_lock);
acpi_release_global_lock(glk); acpi_release_global_lock(glk);
return count;
} }
/* clean up fw_cfg device i/o */ /* clean up fw_cfg device i/o */
@ -183,8 +184,9 @@ static int fw_cfg_do_platform_probe(struct platform_device *pdev)
} }
/* verify fw_cfg device signature */ /* verify fw_cfg device signature */
fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE); if (fw_cfg_read_blob(FW_CFG_SIGNATURE, sig,
if (memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) { 0, FW_CFG_SIG_SIZE) < 0 ||
memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) {
fw_cfg_io_cleanup(); fw_cfg_io_cleanup();
return -ENODEV; return -ENODEV;
} }
@ -344,8 +346,7 @@ static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,
if (count > entry->size - pos) if (count > entry->size - pos)
count = entry->size - pos; count = entry->size - pos;
fw_cfg_read_blob(entry->select, buf, pos, count); return fw_cfg_read_blob(entry->select, buf, pos, count);
return count;
} }
static struct bin_attribute fw_cfg_sysfs_attr_raw = { static struct bin_attribute fw_cfg_sysfs_attr_raw = {
@ -501,7 +502,11 @@ static int fw_cfg_register_dir_entries(void)
struct fw_cfg_file *dir; struct fw_cfg_file *dir;
size_t dir_size; 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); count = be32_to_cpu(files_count);
dir_size = count * sizeof(struct fw_cfg_file); dir_size = count * sizeof(struct fw_cfg_file);
@ -509,7 +514,10 @@ static int fw_cfg_register_dir_entries(void)
if (!dir) if (!dir)
return -ENOMEM; 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++) { for (i = 0; i < count; i++) {
ret = fw_cfg_register_file(&dir[i]); ret = fw_cfg_register_file(&dir[i]);
@ -517,6 +525,7 @@ static int fw_cfg_register_dir_entries(void)
break; break;
} }
end:
kfree(dir); kfree(dir);
return ret; return ret;
} }
@ -557,7 +566,10 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev)
goto err_probe; goto err_probe;
/* get revision number, add matching top-level attribute */ /* 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); fw_cfg_rev = le32_to_cpu(rev);
err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr); err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
if (err) if (err)