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adfs: fix E+/F+ dir size > 2048 crashing kernel

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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>
This commit is contained in:
Stuart Swales 2011-03-22 16:35:04 -07:00 committed by Linus Torvalds
parent 12da58b0c8
commit 2f09719af7
2 changed files with 84 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/adfs/adfs.h
View File

@ -79,6 +79,10 @@ struct adfs_dir {
int nr_buffers;
struct buffer_head *bh[4];
/* big directories need allocated buffers */
struct buffer_head **bh_fplus;
unsigned int pos;
unsigned int parent_id;

101
fs/adfs/dir_fplus.c
View File

@ -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 @@ adfs_fplus_read(struct super_block *sb, unsigned int id, unsigned int sz, struct
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 @@ adfs_fplus_read(struct super_block *sb, unsigned int id, unsigned int sz, struct
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 @@ out:
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 @@ dir_memcpy(struct adfs_dir *dir, unsigned int offset, void *to, int len)
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 @@ adfs_fplus_sync(struct adfs_dir *dir)
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 @@ adfs_fplus_free(struct adfs_dir *dir)
{
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;
}