From ff917923f4fb9c83717ba135ee47d7e4c1567bb7 Mon Sep 17 00:00:00 2001 From: Muhammad Bilal Date: Tue, 28 Jul 2026 17:54:55 +0500 Subject: staging: rtl8723bs: fix OOB read in rtw_action_frame_parse() rtw_action_frame_parse() takes a frame_len parameter but never actually checks it before indexing into the frame body: const u8 *frame_body = frame + sizeof(struct ieee80211_hdr_3addr); ... c = frame_body[0]; ... a = frame_body[1]; frame_body already points 24 bytes (sizeof(struct ieee80211_hdr_3addr)) into frame, so reading frame_body[0] and frame_body[1] requires frame_len >= 26. A management action frame shorter than that (e.g. exactly 24 bytes, the minimum a malicious peer can send) causes a 1-2 byte out-of-bounds read. This is reachable from rtw_cfg80211_monitor_if_xmit_entry() and cfg80211_rtw_mgmt_tx() in ioctl_cfg80211.c, both of which pass attacker/user-influenced frame buffers and lengths straight through. Add the missing length check before frame_body is dereferenced. Fixes: 554c0a3abf216 ("staging: Add rtl8723bs sdio wifi driver") Cc: stable@vger.kernel.org Signed-off-by: Muhammad Bilal Link: https://patch.msgid.link/20260728125456.32359-3-meatuni001@gmail.com Signed-off-by: Greg Kroah-Hartman --- Documentation/filesystems/ext4/bigalloc.rst | 34 +++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 Documentation/filesystems/ext4/bigalloc.rst (limited to 'Documentation/filesystems/ext4/bigalloc.rst') diff --git a/Documentation/filesystems/ext4/bigalloc.rst b/Documentation/filesystems/ext4/bigalloc.rst new file mode 100644 index 000000000..976a180b2 --- /dev/null +++ b/Documentation/filesystems/ext4/bigalloc.rst @@ -0,0 +1,34 @@ +.. SPDX-License-Identifier: GPL-2.0 + +Bigalloc +-------- + +At the moment, the default size of a block is 4KiB, which is a commonly +supported page size on most MMU-capable hardware. This is fortunate, as +ext4 code is not prepared to handle the case where the block size +exceeds the page size. However, for a filesystem of mostly huge files, +it is desirable to be able to allocate disk blocks in units of multiple +blocks to reduce both fragmentation and metadata overhead. The +bigalloc feature provides exactly this ability. + +The bigalloc feature (EXT4_FEATURE_RO_COMPAT_BIGALLOC) changes ext4 to +use clustered allocation, so that each bit in the ext4 block allocation +bitmap addresses a power of two number of blocks. For example, if the +file system is mainly going to be storing large files in the 4-32 +megabyte range, it might make sense to set a cluster size of 1 megabyte. +This means that each bit in the block allocation bitmap now addresses +256 4k blocks. This shrinks the total size of the block allocation +bitmaps for a 2T file system from 64 megabytes to 256 kilobytes. It also +means that a block group addresses 32 gigabytes instead of 128 megabytes, +also shrinking the amount of file system overhead for metadata. + +The administrator can set a block cluster size at mkfs time (which is +stored in the s_log_cluster_size field in the superblock); from then +on, the block bitmaps track clusters, not individual blocks. This means +that block groups can be several gigabytes in size (instead of just +128MiB); however, the minimum allocation unit becomes a cluster, not a +block, even for directories. TaoBao had a patchset to extend the “use +units of clusters instead of blocks” to the extent tree, though it is +not clear where those patches went-- they eventually morphed into +“extent tree v2” but that code has not landed as of May 2015. + -- cgit v1.3.1