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afs_fs_probe_fileserver() fetches the current endpoint state under
server->fs_lock, but leaves old_alist as NULL. Consequently,
afs_set_peer_appdata() treats every address list replacement as initial
setup and only binds the new peers; it never unbinds peers removed from
the old list.
An address refresh can therefore proceed as follows. CPU 0 replaces
server S's list and drops Pold without clearing Pold->app_data. The
server destroyer then clears only S's current peers and lets S reach its
RCU callback. After the callback frees S, CPU 1 handles a callback
through an RxRPC connection that still pins Pold, reads Pold->app_data,
and calls afs_use_server() on the freed object.
KASAN reported:
BUG: KASAN: slab-use-after-free in afs_find_server+0x3c/0xa0
Read of size 4 at addr ffff8881013e1af0 by task krxrpcio/7001/74
Call Trace:
afs_find_server+0x3c/0xa0
afs_rx_new_call+0x15c/0x390
rxrpc_new_incoming_call+0x97c/0x1730
rxrpc_input_packet.constprop.0+0xd03/0xec0
rxrpc_io_thread+0x967/0x1640
Allocated by task 93:
afs_lookup_server+0x1a7/0x14c0
afs_alloc_server_list+0x43f/0xb60
afs_create_volume+0x923/0x1490
afs_get_tree+0x1c6/0x10a0
Freed by task 0:
kfree+0x131/0x3c0
rcu_core+0x50a/0x1850
Last potentially related work creation:
__call_rcu_common.constprop.0+0x71/0xa10
afs_put_server+0x213/0x2b0
Preserve old->addresses for the peer app-data update so that removed
peers are cleared before the endpoint state is replaced. Also advance
both cursors when the old and new lists share a peer; activating the
old/new comparison without this would otherwise loop forever on the
shared entry.
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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