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Deepanshu Kartikey
65d4e5af2a
commit53ca00a19dupstream. When CONFIG_SLUB_TINY is enabled, kfree_nolock() calls kasan_slab_free() before defer_free(). On ARM64 with MTE (Memory Tagging Extension), kasan_slab_free() poisons the memory and changes the tag from the original (e.g., 0xf3) to a poison tag (0xfe). When defer_free() then tries to write to the freed object to build the deferred free list via llist_add(), the pointer still has the old tag, causing a tag mismatch and triggering a KASAN use-after-free report: BUG: KASAN: slab-use-after-free in defer_free+0x3c/0xbc mm/slub.c:6537 Write at addr f3f000000854f020 by task kworker/u8:6/983 Pointer tag: [f3], memory tag: [fe] Fix this by calling kasan_reset_tag() before accessing the freed memory. This is safe because defer_free() is part of the allocator itself and is expected to manipulate freed memory for bookkeeping purposes. Fixes:af92793e52("slab: Introduce kmalloc_nolock() and kfree_nolock().") Cc: stable@vger.kernel.org Reported-by: syzbot+7a25305a76d872abcfa1@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7a25305a76d872abcfa1 Tested-by: syzbot+7a25305a76d872abcfa1@syzkaller.appspotmail.com Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Link: https://patch.msgid.link/20251210022024.3255826-1-kartikey406@gmail.com Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.