adfs: fix E+/F+ dir size > 2048 crashing kernel
Kernel crashes in fs/adfs module when accessing directories with a large
number of objects on mounted Acorn ADFS E+/F+ format discs (or images) as
the existing code writes off the end of the fixed array of struct
buffer_head pointers.
Additionally, each directory access that didn't crash would leak a buffer
as nr_buffers was not adjusted correctly for E+/F+ discs (was always left
as one less than required).
The patch fixes this by allocating a dynamically-sized set of struct
buffer_head pointers if necessary for the E+/F+ case (many directories
still do in fact fit in 2048 bytes) and sets the correct nr_buffers so
that all buffers are released.
Addresses https://bugzilla.kernel.org/show_bug.cgi?id=26072
Tested by tar'ing the contents of my RISC PC's E+ format 20Gb HDD which
contains a number of large directories that previously crashed the kernel.
Signed-off-by: Stuart Swales <stuart.swales.croftnuisk@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/adfs/dir_fplus.c b/fs/adfs/dir_fplus.c
index 1796bb35..a7f41da 100644
--- a/fs/adfs/dir_fplus.c
+++ b/fs/adfs/dir_fplus.c
@@ -8,6 +8,7 @@
* published by the Free Software Foundation.
*/
#include <linux/buffer_head.h>
+#include <linux/slab.h>
#include "adfs.h"
#include "dir_fplus.h"
@@ -22,30 +23,53 @@
dir->nr_buffers = 0;
+ /* start off using fixed bh set - only alloc for big dirs */
+ dir->bh_fplus = &dir->bh[0];
+
block = __adfs_block_map(sb, id, 0);
if (!block) {
adfs_error(sb, "dir object %X has a hole at offset 0", id);
goto out;
}
- dir->bh[0] = sb_bread(sb, block);
- if (!dir->bh[0])
+ dir->bh_fplus[0] = sb_bread(sb, block);
+ if (!dir->bh_fplus[0])
goto out;
dir->nr_buffers += 1;
- h = (struct adfs_bigdirheader *)dir->bh[0]->b_data;
+ h = (struct adfs_bigdirheader *)dir->bh_fplus[0]->b_data;
size = le32_to_cpu(h->bigdirsize);
if (size != sz) {
- printk(KERN_WARNING "adfs: adfs_fplus_read: directory header size\n"
- " does not match directory size\n");
+ printk(KERN_WARNING "adfs: adfs_fplus_read:"
+ " directory header size %X\n"
+ " does not match directory size %X\n",
+ size, sz);
}
if (h->bigdirversion[0] != 0 || h->bigdirversion[1] != 0 ||
h->bigdirversion[2] != 0 || size & 2047 ||
- h->bigdirstartname != cpu_to_le32(BIGDIRSTARTNAME))
+ h->bigdirstartname != cpu_to_le32(BIGDIRSTARTNAME)) {
+ printk(KERN_WARNING "adfs: dir object %X has"
+ " malformed dir header\n", id);
goto out;
+ }
size >>= sb->s_blocksize_bits;
+ if (size > sizeof(dir->bh)/sizeof(dir->bh[0])) {
+ /* this directory is too big for fixed bh set, must allocate */
+ struct buffer_head **bh_fplus =
+ kzalloc(size * sizeof(struct buffer_head *),
+ GFP_KERNEL);
+ if (!bh_fplus) {
+ adfs_error(sb, "not enough memory for"
+ " dir object %X (%d blocks)", id, size);
+ goto out;
+ }
+ dir->bh_fplus = bh_fplus;
+ /* copy over the pointer to the block that we've already read */
+ dir->bh_fplus[0] = dir->bh[0];
+ }
+
for (blk = 1; blk < size; blk++) {
block = __adfs_block_map(sb, id, blk);
if (!block) {
@@ -53,25 +77,44 @@
goto out;
}
- dir->bh[blk] = sb_bread(sb, block);
- if (!dir->bh[blk])
+ dir->bh_fplus[blk] = sb_bread(sb, block);
+ if (!dir->bh_fplus[blk]) {
+ adfs_error(sb, "dir object %X failed read for"
+ " offset %d, mapped block %X",
+ id, blk, block);
goto out;
- dir->nr_buffers = blk;
+ }
+
+ dir->nr_buffers += 1;
}
- t = (struct adfs_bigdirtail *)(dir->bh[size - 1]->b_data + (sb->s_blocksize - 8));
+ t = (struct adfs_bigdirtail *)
+ (dir->bh_fplus[size - 1]->b_data + (sb->s_blocksize - 8));
if (t->bigdirendname != cpu_to_le32(BIGDIRENDNAME) ||
t->bigdirendmasseq != h->startmasseq ||
- t->reserved[0] != 0 || t->reserved[1] != 0)
+ t->reserved[0] != 0 || t->reserved[1] != 0) {
+ printk(KERN_WARNING "adfs: dir object %X has "
+ "malformed dir end\n", id);
goto out;
+ }
dir->parent_id = le32_to_cpu(h->bigdirparent);
dir->sb = sb;
return 0;
+
out:
- for (i = 0; i < dir->nr_buffers; i++)
- brelse(dir->bh[i]);
+ if (dir->bh_fplus) {
+ for (i = 0; i < dir->nr_buffers; i++)
+ brelse(dir->bh_fplus[i]);
+
+ if (&dir->bh[0] != dir->bh_fplus)
+ kfree(dir->bh_fplus);
+
+ dir->bh_fplus = NULL;
+ }
+
+ dir->nr_buffers = 0;
dir->sb = NULL;
return ret;
}
@@ -79,7 +122,8 @@
static int
adfs_fplus_setpos(struct adfs_dir *dir, unsigned int fpos)
{
- struct adfs_bigdirheader *h = (struct adfs_bigdirheader *)dir->bh[0]->b_data;
+ struct adfs_bigdirheader *h =
+ (struct adfs_bigdirheader *) dir->bh_fplus[0]->b_data;
int ret = -ENOENT;
if (fpos <= le32_to_cpu(h->bigdirentries)) {
@@ -102,21 +146,27 @@
partial = sb->s_blocksize - offset;
if (partial >= len)
- memcpy(to, dir->bh[buffer]->b_data + offset, len);
+ memcpy(to, dir->bh_fplus[buffer]->b_data + offset, len);
else {
char *c = (char *)to;
remainder = len - partial;
- memcpy(c, dir->bh[buffer]->b_data + offset, partial);
- memcpy(c + partial, dir->bh[buffer + 1]->b_data, remainder);
+ memcpy(c,
+ dir->bh_fplus[buffer]->b_data + offset,
+ partial);
+
+ memcpy(c + partial,
+ dir->bh_fplus[buffer + 1]->b_data,
+ remainder);
}
}
static int
adfs_fplus_getnext(struct adfs_dir *dir, struct object_info *obj)
{
- struct adfs_bigdirheader *h = (struct adfs_bigdirheader *)dir->bh[0]->b_data;
+ struct adfs_bigdirheader *h =
+ (struct adfs_bigdirheader *) dir->bh_fplus[0]->b_data;
struct adfs_bigdirentry bde;
unsigned int offset;
int i, ret = -ENOENT;
@@ -160,7 +210,7 @@
int i;
for (i = dir->nr_buffers - 1; i >= 0; i--) {
- struct buffer_head *bh = dir->bh[i];
+ struct buffer_head *bh = dir->bh_fplus[i];
sync_dirty_buffer(bh);
if (buffer_req(bh) && !buffer_uptodate(bh))
err = -EIO;
@@ -174,8 +224,17 @@
{
int i;
- for (i = 0; i < dir->nr_buffers; i++)
- brelse(dir->bh[i]);
+ if (dir->bh_fplus) {
+ for (i = 0; i < dir->nr_buffers; i++)
+ brelse(dir->bh_fplus[i]);
+
+ if (&dir->bh[0] != dir->bh_fplus)
+ kfree(dir->bh_fplus);
+
+ dir->bh_fplus = NULL;
+ }
+
+ dir->nr_buffers = 0;
dir->sb = NULL;
}