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| author | Phillip Lougher <phillip@squashfs.org.uk> | 2024-10-21 00:22:00 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-10-30 20:14:12 -0700 |
| commit | d31638ff6c5437ca2968d6c22fb16524fd485013 (patch) | |
| tree | 64948463ca950201cb89248b4b22514bf8ffb735 | |
| parent | 330d8df81f3673d6fb74550bbc9bb159d81b35f7 (diff) | |
| download | linux-d31638ff6c5437ca2968d6c22fb16524fd485013.tar.gz linux-d31638ff6c5437ca2968d6c22fb16524fd485013.tar.bz2 linux-d31638ff6c5437ca2968d6c22fb16524fd485013.zip | |
Squashfs: fix variable overflow in squashfs_readpage_block
Syzbot reports a slab out of bounds access in squashfs_readpage_block().
This is caused by an attempt to read page index 0x2000000000. This value
(start_index) is stored in an integer loop variable which overflows
producing a value of 0. This causes a loop which iterates over pages
start_index -> end_index to iterate over 0 -> end_index, which ultimately
causes an out of bounds page array access.
Fix by changing variable to a loff_t, and rename to index to make it
clearer it is a page index, and not a loop count.
Link: https://lkml.kernel.org/r/20241020232200.837231-1-phillip@squashfs.org.uk
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reported-by: "Lai, Yi" <yi1.lai@linux.intel.com>
Closes: https://lore.kernel.org/all/ZwzcnCAosIPqQ9Ie@ly-workstation/
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | fs/squashfs/file_direct.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/fs/squashfs/file_direct.c b/fs/squashfs/file_direct.c index 22251743fadf..d19d4db74af8 100644 --- a/fs/squashfs/file_direct.c +++ b/fs/squashfs/file_direct.c @@ -30,7 +30,8 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize, int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1; loff_t start_index = folio->index & ~mask; loff_t end_index = start_index | mask; - int i, n, pages, bytes, res = -ENOMEM; + loff_t index; + int i, pages, bytes, res = -ENOMEM; struct page **page, *last_page; struct squashfs_page_actor *actor; void *pageaddr; @@ -45,9 +46,9 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize, return res; /* Try to grab all the pages covered by the Squashfs block */ - for (i = 0, n = start_index; n <= end_index; n++) { - page[i] = (n == folio->index) ? target_page : - grab_cache_page_nowait(target_page->mapping, n); + for (i = 0, index = start_index; index <= end_index; index++) { + page[i] = (index == folio->index) ? target_page : + grab_cache_page_nowait(target_page->mapping, index); if (page[i] == NULL) continue; |