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ocfs2_validate_inode_block() already rejects several inconsistent
self-contained dinodes before they are exposed to the rest of the
filesystem. Fast symlinks need the same treatment.
A zero-cluster symlink is treated as a fast symlink and later read through
page_get_link() and ocfs2_fast_symlink_read_folio(). That path uses
strnlen() on the inline payload and then copies len + 1 bytes into the
folio. If a corrupt dinode stores an i_size that does not fit the inline
area or omits the terminating NUL at i_size, that copy reads past the end
of the inode block buffer.
Reject zero-cluster symlink dinodes whose i_size exceeds the inline
fast-symlink capacity or whose inline payload is not NUL-terminated
exactly at i_size when the inode block is validated. This keeps malformed
fast symlinks from reaching the read path.
Validation reproduced this kernel report:
KASAN use-after-free in ocfs2_fast_symlink_read_folio+0x12c/0x1f0
RIP: 0033:0x7f5c6d859aa7
Read of size 3905
Call trace:
dump_stack_lvl+0x66/0xa0 (?:?)
print_report+0xce/0x630 (?:?)
ocfs2_fast_symlink_read_folio+0x12c/0x1f0 (fs/ocfs2/inode.c:?)
srso_alias_return_thunk+0x5/0xfbef5 (?:?)
__virt_addr_valid+0x19f/0x330 (?:?)
kasan_report+0xe0/0x110 (?:?)
kasan_check_range+0x105/0x1b0 (?:?)
__asan_memcpy+0x23/0x60 (?:?)
filemap_read_folio+0x27/0xe0 (?:?)
filemap_read_folio+0x35/0xe0 (?:?)
do_read_cache_folio+0x138/0x230 (?:?)
__page_get_link+0x26/0x110 (?:?)
page_get_link+0x2e/0x70 (?:?)
vfs_readlink+0x15e/0x250 (?:?)
touch_atime+0x4d/0x370 (?:?)
do_readlinkat+0x186/0x200 (?:?)
do_user_addr_fault+0x65a/0x890 (?:?)
__x64_sys_readlink+0x46/0x60 (?:?)
do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)
entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)
Link: https://lore.kernel.org/20260528151230.361127-1-rollkingzzc@gmail.com
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. 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