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From 9561d7ef621e5e68f12bcd916252ef1c11e60366 Mon Sep 17 00:00:00 2001
From: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Date: Wed, 6 Apr 2022 18:49:09 +0530
Subject: fs/f2fs: Do not read past the end of nat bitmap
A corrupt f2fs filesystem could have a block offset or a bitmap
offset that would cause us to read beyond the bounds of the nat
bitmap.
Introduce the nat_bitmap_size member in grub_f2fs_data which holds
the size of nat bitmap.
Set the size when loading the nat bitmap in nat_bitmap_ptr(), and
catch when an invalid offset would create a pointer past the end of
the allocated space.
Check against the bitmap size in grub_f2fs_test_bit() test bit to avoid
reading past the end of the nat bitmap.
Signed-off-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/fs/f2fs.c | 33 +++++++++++++++++++++++++++------
1 file changed, 27 insertions(+), 6 deletions(-)
diff --git a/grub-core/fs/f2fs.c b/grub-core/fs/f2fs.c
index 63702214b..8898b235e 100644
--- a/grub-core/fs/f2fs.c
+++ b/grub-core/fs/f2fs.c
@@ -122,6 +122,7 @@ GRUB_MOD_LICENSE ("GPLv3+");
#define F2FS_INLINE_DOTS 0x10 /* File having implicit dot dentries. */
#define MAX_VOLUME_NAME 512
+#define MAX_NAT_BITMAP_SIZE 3900
enum FILE_TYPE
{
@@ -183,7 +184,7 @@ struct grub_f2fs_checkpoint
grub_uint32_t checksum_offset;
grub_uint64_t elapsed_time;
grub_uint8_t alloc_type[MAX_ACTIVE_LOGS];
- grub_uint8_t sit_nat_version_bitmap[3900];
+ grub_uint8_t sit_nat_version_bitmap[MAX_NAT_BITMAP_SIZE];
grub_uint32_t checksum;
} GRUB_PACKED;
@@ -302,6 +303,7 @@ struct grub_f2fs_data
struct grub_f2fs_nat_journal nat_j;
char *nat_bitmap;
+ grub_uint32_t nat_bitmap_size;
grub_disk_t disk;
struct grub_f2fs_node *inode;
@@ -377,15 +379,20 @@ sum_blk_addr (struct grub_f2fs_data *data, int base, int type)
}
static void *
-nat_bitmap_ptr (struct grub_f2fs_data *data)
+nat_bitmap_ptr (struct grub_f2fs_data *data, grub_uint32_t *nat_bitmap_size)
{
struct grub_f2fs_checkpoint *ckpt = &data->ckpt;
grub_uint32_t offset;
+ *nat_bitmap_size = MAX_NAT_BITMAP_SIZE;
if (grub_le_to_cpu32 (data->sblock.cp_payload) > 0)
return ckpt->sit_nat_version_bitmap;
offset = grub_le_to_cpu32 (ckpt->sit_ver_bitmap_bytesize);
+ if (offset >= MAX_NAT_BITMAP_SIZE)
+ return NULL;
+
+ *nat_bitmap_size = *nat_bitmap_size - offset;
return ckpt->sit_nat_version_bitmap + offset;
}
@@ -438,11 +445,15 @@ grub_f2fs_crc_valid (grub_uint32_t blk_crc, void *buf, const grub_uint32_t len)
}
static int
-grub_f2fs_test_bit (grub_uint32_t nr, const char *p)
+grub_f2fs_test_bit (grub_uint32_t nr, const char *p, grub_uint32_t len)
{
int mask;
+ grub_uint32_t shifted_nr = (nr >> 3);
+
+ if (shifted_nr >= len)
+ return -1;
- p += (nr >> 3);
+ p += shifted_nr;
mask = 1 << (7 - (nr & 0x07));
return mask & *p;
@@ -662,6 +673,7 @@ get_node_blkaddr (struct grub_f2fs_data *data, grub_uint32_t nid)
grub_uint32_t seg_off, block_off, entry_off, block_addr;
grub_uint32_t blkaddr = 0;
grub_err_t err;
+ int result_bit;
err = get_blkaddr_from_nat_journal (data, nid, &blkaddr);
if (err != GRUB_ERR_NONE)
@@ -682,8 +694,15 @@ get_node_blkaddr (struct grub_f2fs_data *data, grub_uint32_t nid)
((seg_off * data->blocks_per_seg) << 1) +
(block_off & (data->blocks_per_seg - 1));
- if (grub_f2fs_test_bit (block_off, data->nat_bitmap))
+ result_bit = grub_f2fs_test_bit (block_off, data->nat_bitmap,
+ data->nat_bitmap_size);
+ if (result_bit > 0)
block_addr += data->blocks_per_seg;
+ else if (result_bit == -1)
+ {
+ grub_free (nat_block);
+ return 0;
+ }
err = grub_f2fs_block_read (data, block_addr, nat_block);
if (err)
@@ -833,7 +852,9 @@ grub_f2fs_mount (grub_disk_t disk)
if (err)
goto fail;
- data->nat_bitmap = nat_bitmap_ptr (data);
+ data->nat_bitmap = nat_bitmap_ptr (data, &data->nat_bitmap_size);
+ if (data->nat_bitmap == NULL)
+ goto fail;
err = get_nat_journal (data);
if (err)
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