[PATCH v2 1/2] disk/part.c: ensure strings in struct disk_partition are valid after successful get_info
Rasmus Villemoes
ravi at prevas.dk
Mon Oct 20 14:10:59 CEST 2025
Not all ->get_info implementations necessarily populate all the string
members of struct disk_partition.
Currently, only part_get_info_by_type() (and thereby part_get_info)
ensure that the uuid strings are initialized; part_get_info_by_type()
and part_get_info_by_uuid() do not. In fact, the latter could lead to
a false positive match - if the ->get_info backend does not populate
info->uuid, stale contents in info could cause the strncasecmp() to
succeed.
None of the functions currently ensure that the ->name and ->type
strings are initialized.
Instead of forcing all callers of any of these functions to
pre-initialize info, or all implementations of the ->get_info method
to ensure there are valid C strings in all four fields, create a small
helper function and factor all invocations of ->get_info through that.
This also consolidates the -ENOSYS check and standardizes on using
log_debug() for reporting absence, instead of the current mix of
PRINTF and log_debug(). It does mean we have to special-case -ENOSYS
in the error cases inside the loops in the _by_uuid() and _by_name()
functions, but it's still a net win in #LOC.
Signed-off-by: Rasmus Villemoes <ravi at prevas.dk>
---
v2: new patch in v2.
cmd/gpt.c | 4 ++--
disk/part.c | 62 ++++++++++++++++++++++++++++----------------------
include/part.h | 16 +++++++++++++
3 files changed, 53 insertions(+), 29 deletions(-)
diff --git a/cmd/gpt.c b/cmd/gpt.c
index e18e5036a06..84221881c39 100644
--- a/cmd/gpt.c
+++ b/cmd/gpt.c
@@ -724,7 +724,7 @@ static int gpt_enumerate(struct blk_desc *desc)
continue;
for (i = 1; i < part_drv->max_entries; i++) {
- ret = part_drv->get_info(desc, i, &pinfo);
+ ret = part_driver_get_info(part_drv, desc, i, &pinfo);
if (ret)
continue;
@@ -820,7 +820,7 @@ static int gpt_setenv(struct blk_desc *desc, const char *name)
int i;
for (i = 1; i < part_drv->max_entries; i++) {
- ret = part_drv->get_info(desc, i, &pinfo);
+ ret = part_driver_get_info(part_drv, desc, i, &pinfo);
if (ret)
continue;
diff --git a/disk/part.c b/disk/part.c
index be2b45d5a29..194eccadb7b 100644
--- a/disk/part.c
+++ b/disk/part.c
@@ -72,6 +72,28 @@ struct part_driver *part_driver_lookup_type(struct blk_desc *desc)
return NULL;
}
+static void disk_partition_clr(struct disk_partition *info)
+{
+ /* The common case is no UUID support */
+ disk_partition_clr_uuid(info);
+ disk_partition_clr_type_guid(info);
+ info->name[0] = '\0';
+ info->type[0] = '\0';
+}
+
+int part_driver_get_info(struct part_driver *drv, struct blk_desc *desc, int part,
+ struct disk_partition *info)
+{
+ if (!drv->get_info) {
+ log_debug("## Driver %s does not have the get_info() method\n",
+ drv->name);
+ return -ENOSYS;
+ }
+
+ disk_partition_clr(info);
+ return drv->get_info(desc, part, info);
+}
+
int part_get_type_by_name(const char *name)
{
struct part_driver *drv =
@@ -322,12 +344,9 @@ int part_get_info_by_type(struct blk_desc *desc, int part, int part_type,
struct disk_partition *info)
{
struct part_driver *drv;
+ int ret = -ENOENT;
if (blk_enabled()) {
- /* The common case is no UUID support */
- disk_partition_clr_uuid(info);
- disk_partition_clr_type_guid(info);
-
if (part_type == PART_TYPE_UNKNOWN) {
drv = part_driver_lookup_type(desc);
} else {
@@ -339,18 +358,13 @@ int part_get_info_by_type(struct blk_desc *desc, int part, int part_type,
desc->part_type);
return -EPROTONOSUPPORT;
}
- if (!drv->get_info) {
- PRINTF("## Driver %s does not have the get_info() method\n",
- drv->name);
- return -ENOSYS;
- }
- if (drv->get_info(desc, part, info) == 0) {
+
+ ret = part_driver_get_info(drv, desc, part, info);
+ if (!ret)
PRINTF("## Valid %s partition found ##\n", drv->name);
- return 0;
- }
}
- return -ENOENT;
+ return ret;
}
int part_get_info(struct blk_desc *desc, int part,
@@ -657,15 +671,12 @@ int part_get_info_by_name(struct blk_desc *desc, const char *name,
if (!part_drv)
return -1;
- if (!part_drv->get_info) {
- log_debug("## Driver %s does not have the get_info() method\n",
- part_drv->name);
- return -ENOSYS;
- }
-
for (i = 1; i < part_drv->max_entries; i++) {
- ret = part_drv->get_info(desc, i, info);
+ ret = part_driver_get_info(part_drv, desc, i, info);
if (ret != 0) {
+ /* -ENOSYS means no ->get_info method. */
+ if (ret == -ENOSYS)
+ return ret;
/*
* Partition with this index can't be obtained, but
* further partitions might be, so keep checking.
@@ -695,15 +706,12 @@ int part_get_info_by_uuid(struct blk_desc *desc, const char *uuid,
if (!part_drv)
return -1;
- if (!part_drv->get_info) {
- log_debug("## Driver %s does not have the get_info() method\n",
- part_drv->name);
- return -ENOSYS;
- }
-
for (i = 1; i < part_drv->max_entries; i++) {
- ret = part_drv->get_info(desc, i, info);
+ ret = part_driver_get_info(part_drv, desc, i, info);
if (ret != 0) {
+ /* -ENOSYS means no ->get_info method. */
+ if (ret == -ENOSYS)
+ return ret;
/*
* Partition with this index can't be obtained, but
* further partitions might be, so keep checking.
diff --git a/include/part.h b/include/part.h
index 6caaa6526aa..d940f8b5d0e 100644
--- a/include/part.h
+++ b/include/part.h
@@ -509,6 +509,22 @@ struct part_driver {
int (*test)(struct blk_desc *desc);
};
+/**
+ * part_driver_get_info() - Call the part_driver's get_info method
+ *
+ * On success, string members of info are guaranteed to be properly
+ * initialized, though they may be empty.
+ *
+ * @drv: Partition driver
+ * @desc: Block device descriptor
+ * @part: Partition number to read
+ * @info: Returned partition information
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int part_driver_get_info(struct part_driver *drv, struct blk_desc *desc, int part,
+ struct disk_partition *info);
+
/* Declare a new U-Boot partition 'driver' */
#define U_BOOT_PART_TYPE(__name) \
ll_entry_declare(struct part_driver, __name, part_driver)
--
2.51.0
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