ext4: add positive int attr pointer to avoid sysfs variables overflow

The following variables controlled by the sysfs interface are of type
int and are normally used in the range [0, INT_MAX], but are declared as
attr_pointer_ui, and thus may be set to values that exceed INT_MAX and
result in overflows to get negative values.

  err_ratelimit_burst
  msg_ratelimit_burst
  warning_ratelimit_burst
  err_ratelimit_interval_ms
  msg_ratelimit_interval_ms
  warning_ratelimit_interval_ms

Therefore, we add attr_pointer_pi (aka positive int attr pointer) with a
value range of 0-INT_MAX to avoid overflow.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240319113325.3110393-7-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index 8e04731694587aefaee851e4402d4dd50f823d7f..ddb54608ca2ef6f9eb3d1e49361a024d9a88b339 100644 (file)
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -32,6 +32,7 @@ typedef enum {
        attr_clusters_in_group,
        attr_mb_order,
        attr_feature,
+       attr_pointer_pi,
        attr_pointer_ui,
        attr_pointer_ul,
        attr_pointer_u64,
@@ -180,6 +181,9 @@ static struct ext4_attr ext4_attr_##_name = {                       \
 #define EXT4_RO_ATTR_ES_STRING(_name,_elname,_size)                    \
        EXT4_ATTR_STRING(_name, 0444, _size, ext4_super_block, _elname)
 
+#define EXT4_RW_ATTR_SBI_PI(_name,_elname)      \
+       EXT4_ATTR_OFFSET(_name, 0644, pointer_pi, ext4_sb_info, _elname)
+
 #define EXT4_RW_ATTR_SBI_UI(_name,_elname)     \
        EXT4_ATTR_OFFSET(_name, 0644, pointer_ui, ext4_sb_info, _elname)
 
@@ -222,12 +226,12 @@ EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
 EXT4_RW_ATTR_SBI_UI(mb_max_linear_groups, s_mb_max_linear_groups);
 EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
 EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error);
-EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
-EXT4_RW_ATTR_SBI_UI(err_ratelimit_burst, s_err_ratelimit_state.burst);
-EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval);
-EXT4_RW_ATTR_SBI_UI(warning_ratelimit_burst, s_warning_ratelimit_state.burst);
-EXT4_RW_ATTR_SBI_UI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval);
-EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst);
+EXT4_RW_ATTR_SBI_PI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
+EXT4_RW_ATTR_SBI_PI(err_ratelimit_burst, s_err_ratelimit_state.burst);
+EXT4_RW_ATTR_SBI_PI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval);
+EXT4_RW_ATTR_SBI_PI(warning_ratelimit_burst, s_warning_ratelimit_state.burst);
+EXT4_RW_ATTR_SBI_PI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval);
+EXT4_RW_ATTR_SBI_PI(msg_ratelimit_burst, s_msg_ratelimit_state.burst);
 #ifdef CONFIG_EXT4_DEBUG
 EXT4_RW_ATTR_SBI_UL(simulate_fail, s_simulate_fail);
 #endif
@@ -382,6 +386,7 @@ static ssize_t ext4_generic_attr_show(struct ext4_attr *a,
        case attr_inode_readahead:
        case attr_clusters_in_group:
        case attr_mb_order:
+       case attr_pointer_pi:
        case attr_pointer_ui:
                if (a->attr_ptr == ptr_ext4_super_block_offset)
                        return sysfs_emit(buf, "%u\n", le32_to_cpup(ptr));
@@ -452,6 +457,14 @@ static ssize_t ext4_generic_attr_store(struct ext4_attr *a,
                return 0;
 
        switch (a->attr_id) {
+       case attr_pointer_pi:
+               ret = kstrtouint(skip_spaces(buf), 0, &t);
+               if (ret)
+                       return ret;
+               if ((int)t < 0)
+                       return -EINVAL;
+               *((unsigned int *) ptr) = t;
+               return len;
        case attr_pointer_ui:
                ret = kstrtouint(skip_spaces(buf), 0, &t);
                if (ret)