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Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1teiBg-0000000HXyC-2g6x; Sun, 02 Feb 2025 22:11:32 +0000 Date: Sun, 2 Feb 2025 22:11:32 +0000 From: Matthew Wilcox To: syzbot Cc: akpm@linux-foundation.org, hughd@google.com, kent.overstreet@linux.dev, linux-bcachefs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [mm?] [bcachefs?] UBSAN: shift-out-of-bounds in filemap_get_entry Message-ID: References: <679fb148.050a0220.d7c5a.0074.GAE@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <679fb148.050a0220.d7c5a.0074.GAE@google.com> X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: ECF3FC0002 X-Stat-Signature: 8xzah4373kk5oayj3ro6ma1dax85aeku X-Rspam-User: X-HE-Tag: 1738534296-809486 X-HE-Meta: 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 +SwHumz0 R6a+IeKNQ0PcRLJ+AYoQytYVVjsb16FYeHqZUMyNsq2Z2Nkl2Vn68unmj9oee1CM7eOzkiz9rmdJDe1iHJrMlcafXB/NgFRWdJGBad6klB+Fsk6pR1bZKo0qOZj/lajh+3owE9owXWvJL3IChwnavYXjen9F4xLeVN4ajnGd6/NV+cpnQPbJ+owDhmFOR8O8SW8SYwJciDvYeynwriN+wzYF43Yqlku9M4wKrpQgx/rXMbXBY92oMJ1ubb5Wbqq4Vcvkrn/mmhkFwj0mVbCtiPCLImorSaMbFonOt+4aOxxXnz/0I1le567kvOvSftoECADgiVPv+w6Nco7+Eu5NgLIpMHzVChseyB3+KdBi0D36y5GLuaRMXEp65Hhrx+T2lOk5sLwWTEKRdU5rFi+ZAJnC1jWKKes1KYX2a X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Feb 02, 2025 at 09:54:16AM -0800, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 69e858e0b8b2 Merge tag 'uml-for-linus-6.14-rc1' of git://g.. > > ------------[ cut here ]------------ > UBSAN: shift-out-of-bounds in lib/xarray.c:147:16 > shift exponent 192 is too large for 64-bit type 'unsigned long' > CPU: 0 UID: 0 PID: 2666 Comm: kworker/u4:9 Not tainted 6.13.0-syzkaller-09760-g69e858e0b8b2 #0 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 > Workqueue: loop0 loop_rootcg_workfn > Call Trace: > > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 > ubsan_epilogue lib/ubsan.c:231 [inline] > __ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468 > get_offset lib/xarray.c:147 [inline] > xas_descend lib/xarray.c:207 [inline] > xas_load+0x583/0x5c0 lib/xarray.c:246 > filemap_get_entry+0x1f0/0x3b0 mm/filemap.c:1860 This is an xarray issue. I suspect it's a race condition, although it could be somebody doing a misplaced DMA or something. How easy is it to reproduce? (nb: I am on holiday for the next week, so I'm not going to be focused on this, I just don't want other people wasting their time looking for a bug somewhere that it isn't)