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author | 2023-09-25 06:13:12 +0000 | |
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committer | 2023-10-23 13:02:05 -0400 | |
commit | ac4149ba7efd6bc327c1e15e812091984f3a16b2 (patch) | |
tree | abdae55ab7fb5a4dd29b56e75aedc6bf003f35d9 | |
parent | dm: shortcut the calls to linear_map and stripe_map (diff) | |
download | linux-ac4149ba7efd6bc327c1e15e812091984f3a16b2.tar.gz linux-ac4149ba7efd6bc327c1e15e812091984f3a16b2.tar.bz2 linux-ac4149ba7efd6bc327c1e15e812091984f3a16b2.zip |
dm cache metadata: replace deprecated strncpy with strscpy
`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
It seems `cmd->policy_name` is intended to be NUL-terminated based on a
now changed line of code from Commit (c6b4fcbad044e6ff "dm: add cache
target"):
| if (strcmp(cmd->policy_name, policy_name)) { // ...
However, now a length-bounded strncmp is used:
| if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
... which means NUL-terminated may not strictly be required. However, I
believe the intent of the code is clear and we should maintain
NUL-termination of policy_names.
Moreover, __begin_transaction_flags() zero-allocates `cmd` before
calling read_superblock_fields():
| cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
Also, `disk_super->policy_name` is zero-initialized
| memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
... therefore any NUL-padding is redundant.
Considering the above, a suitable replacement is `strscpy` [2] due to
the fact that it guarantees NUL-termination on the destination buffer
without unnecessarily NUL-padding.
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
-rw-r--r-- | drivers/md/dm-cache-metadata.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c index acffed750e3e..5a18b80d3666 100644 --- a/drivers/md/dm-cache-metadata.c +++ b/drivers/md/dm-cache-metadata.c @@ -597,7 +597,7 @@ static void read_superblock_fields(struct dm_cache_metadata *cmd, cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks)); cmd->data_block_size = le32_to_cpu(disk_super->data_block_size); cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks)); - strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name)); + strscpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name)); cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]); cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]); cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]); @@ -707,7 +707,7 @@ static int __commit_transaction(struct dm_cache_metadata *cmd, disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size); disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks)); disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks)); - strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name)); + strscpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name)); disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]); disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]); disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]); @@ -1726,7 +1726,7 @@ static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *po (strlen(policy_name) > sizeof(cmd->policy_name) - 1)) return -EINVAL; - strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name)); + strscpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name)); memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version)); hint_size = dm_cache_policy_get_hint_size(policy); |