In the Linux kernel, the following vulnerability has been resolved:
isofs: fix out-of-bounds page array access on empty zisofs block
zisofs_uncompress_block()'s empty-block fast path returns
pcount << PAGE_SHIFT, ignoring the incoming poffset, unlike the
decompression path which returns bytes produced relative to poffset.
zisofs_fill_pages() uses that return to advance its page cursor, so when
the zisofs block size is below PAGE_SIZE and a sub-page block leaves
poffset partway into a page, a following empty block over-counts and
advances pages[] one element past its end, after which
"if (poffset && *pages)" reads pages[1] out of bounds. rock.c only
rejects a block-size shift > 17, so a crafted "ZF" Rock Ridge record can
set it below PAGE_SHIFT; the bug is reached by an ordinary read() of a
compressed file on such a mounted ISO9660 image.
Return the byte count relative to poffset and zero only
[poffset, PAGE_SIZE) of the first page, matching the decompression path.
The page-aligned case (poffset == 0) is unaffected.
BUG: KASAN: slab-out-of-bounds in zisofs_read_folio (fs/isofs/compress.c:290)
Read of size 8 at addr ffff88800f5eac48 by task exploit/142
zisofs_read_folio (fs/isofs/compress.c:290)
read_pages (mm/readahead.c:184)
...
filemap_read (mm/filemap.c:2814)
vfs_read (fs/read_write.c:574)
__x64_sys_pread64 (fs/read_write.c:769)
do_syscall_64 (arch/x86/entry/syscall_64.c:94)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
The buggy address is located 0 bytes to the right of the
allocated 8-byte region in the kmalloc-8 cache
isofs: fix out-of-bounds page array access on empty zisofs block
zisofs_uncompress_block()'s empty-block fast path returns
pcount << PAGE_SHIFT, ignoring the incoming poffset, unlike the
decompression path which returns bytes produced relative to poffset.
zisofs_fill_pages() uses that return to advance its page cursor, so when
the zisofs block size is below PAGE_SIZE and a sub-page block leaves
poffset partway into a page, a following empty block over-counts and
advances pages[] one element past its end, after which
"if (poffset && *pages)" reads pages[1] out of bounds. rock.c only
rejects a block-size shift > 17, so a crafted "ZF" Rock Ridge record can
set it below PAGE_SHIFT; the bug is reached by an ordinary read() of a
compressed file on such a mounted ISO9660 image.
Return the byte count relative to poffset and zero only
[poffset, PAGE_SIZE) of the first page, matching the decompression path.
The page-aligned case (poffset == 0) is unaffected.
BUG: KASAN: slab-out-of-bounds in zisofs_read_folio (fs/isofs/compress.c:290)
Read of size 8 at addr ffff88800f5eac48 by task exploit/142
zisofs_read_folio (fs/isofs/compress.c:290)
read_pages (mm/readahead.c:184)
...
filemap_read (mm/filemap.c:2814)
vfs_read (fs/read_write.c:574)
__x64_sys_pread64 (fs/read_write.c:769)
do_syscall_64 (arch/x86/entry/syscall_64.c:94)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
The buggy address is located 0 bytes to the right of the
allocated 8-byte region in the kmalloc-8 cache
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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Advisories
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Fixes
Solution
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Workaround
No workaround given by the vendor.
References
History
Wed, 16 Sep 2026 09:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: isofs: fix out-of-bounds page array access on empty zisofs block zisofs_uncompress_block()'s empty-block fast path returns pcount << PAGE_SHIFT, ignoring the incoming poffset, unlike the decompression path which returns bytes produced relative to poffset. zisofs_fill_pages() uses that return to advance its page cursor, so when the zisofs block size is below PAGE_SIZE and a sub-page block leaves poffset partway into a page, a following empty block over-counts and advances pages[] one element past its end, after which "if (poffset && *pages)" reads pages[1] out of bounds. rock.c only rejects a block-size shift > 17, so a crafted "ZF" Rock Ridge record can set it below PAGE_SHIFT; the bug is reached by an ordinary read() of a compressed file on such a mounted ISO9660 image. Return the byte count relative to poffset and zero only [poffset, PAGE_SIZE) of the first page, matching the decompression path. The page-aligned case (poffset == 0) is unaffected. BUG: KASAN: slab-out-of-bounds in zisofs_read_folio (fs/isofs/compress.c:290) Read of size 8 at addr ffff88800f5eac48 by task exploit/142 zisofs_read_folio (fs/isofs/compress.c:290) read_pages (mm/readahead.c:184) ... filemap_read (mm/filemap.c:2814) vfs_read (fs/read_write.c:574) __x64_sys_pread64 (fs/read_write.c:769) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) The buggy address is located 0 bytes to the right of the allocated 8-byte region in the kmalloc-8 cache | |
| Title | isofs: fix out-of-bounds page array access on empty zisofs block | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-16T08:48:18.407Z
Reserved: 2026-09-11T19:38:34.765Z
Link: CVE-2026-89778
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-16T09:17:08.253
Modified: 2026-09-16T09:17:08.253
Link: CVE-2026-89778
Redhat
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OpenCVE Enrichment
No data.
Weaknesses
No weakness.