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[PATCH 1/1] fs/udf: Fix out of bounds access
From: |
Lidong Chen |
Subject: |
[PATCH 1/1] fs/udf: Fix out of bounds access |
Date: |
Thu, 1 Jun 2023 18:50:19 +0000 |
Implemented a boundary check before advancing the allocation
descriptors pointer.
Signed-off-by: Lidong Chen <lidong.chen@oracle.com>
---
grub-core/fs/udf.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/grub-core/fs/udf.c b/grub-core/fs/udf.c
index 12e88ab62..2359222eb 100644
--- a/grub-core/fs/udf.c
+++ b/grub-core/fs/udf.c
@@ -458,6 +458,7 @@ grub_udf_read_block (grub_fshelp_node_t node,
grub_disk_addr_t fileblock)
char *ptr;
grub_ssize_t len;
grub_disk_addr_t filebytes;
+ char *end_ptr;
switch (U16 (node->block.fe.tag.tag_ident))
{
@@ -476,9 +477,17 @@ grub_udf_read_block (grub_fshelp_node_t node,
grub_disk_addr_t fileblock)
return 0;
}
+ end_ptr = (char *) node + get_fshelp_size (node->data);
+
if ((U16 (node->block.fe.icbtag.flags) & GRUB_UDF_ICBTAG_FLAG_AD_MASK)
== GRUB_UDF_ICBTAG_FLAG_AD_SHORT)
{
+ if ((end_ptr - ptr) < (grub_ssize_t) sizeof (struct grub_udf_short_ad))
+ {
+ grub_error (GRUB_ERR_BAD_FS, "corrupted UDF file system");
+ return 0;
+ }
+
struct grub_udf_short_ad *ad = (struct grub_udf_short_ad *) ptr;
filebytes = fileblock * U32 (node->data->lvd.bsize);
@@ -528,10 +537,23 @@ grub_udf_read_block (grub_fshelp_node_t node,
grub_disk_addr_t fileblock)
filebytes -= adlen;
ad++;
len -= sizeof (struct grub_udf_short_ad);
+
+ if ((char *) ad >= end_ptr ||
+ (end_ptr - (char *) ad) < (grub_ssize_t) sizeof (struct
grub_udf_short_ad))
+ {
+ grub_error (GRUB_ERR_BAD_FS, "corrupted UDF file system");
+ return 0;
+ }
}
}
else
{
+ if ((end_ptr - ptr) < (grub_ssize_t) sizeof (struct grub_udf_long_ad))
+ {
+ grub_error (GRUB_ERR_BAD_FS, "corrupted UDF file system");
+ return 0;
+ }
+
struct grub_udf_long_ad *ad = (struct grub_udf_long_ad *) ptr;
filebytes = fileblock * U32 (node->data->lvd.bsize);
@@ -583,6 +605,13 @@ grub_udf_read_block (grub_fshelp_node_t node,
grub_disk_addr_t fileblock)
filebytes -= adlen;
ad++;
len -= sizeof (struct grub_udf_long_ad);
+
+ if ((char *) ad >= end_ptr ||
+ (end_ptr - (char *) ad) < (grub_ssize_t) sizeof (struct
grub_udf_long_ad))
+ {
+ grub_error (GRUB_ERR_BAD_FS, "corrupted UDF file system");
+ return 0;
+ }
}
}
@@ -602,6 +631,7 @@ grub_udf_read_file (grub_fshelp_node_t node,
case GRUB_UDF_ICBTAG_FLAG_AD_IN_ICB:
{
char *ptr;
+ char *end_ptr = (char *) node + get_fshelp_size (node->data);
ptr = ((U16 (node->block.fe.tag.tag_ident) == GRUB_UDF_TAG_IDENT_FE) ?
((char *) &node->block.fe.ext_attr[0]
@@ -609,6 +639,12 @@ grub_udf_read_file (grub_fshelp_node_t node,
((char *) &node->block.efe.ext_attr[0]
+ U32 (node->block.efe.ext_attr_length)));
+ if (ptr > end_ptr || (ptr + pos) > end_ptr || (ptr + pos + len) >
end_ptr)
+ {
+ grub_error (GRUB_ERR_BAD_FS, "corrupted UDF file system");
+ return 0;
+ }
+
grub_memcpy (buf, ptr + pos, len);
return len;
--
2.39.1
- [PATCH 1/1] fs/udf: Fix out of bounds access,
Lidong Chen <=