From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 090A119D09C; Tue, 15 Jul 2025 13:19:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752585578; cv=none; b=kfZh1rYYvR3mH+pAGc4Dv03Xj7djvkWHwiMIgIw47uqFEkgC/ZRqq6sqtgMN+M5vrN+zn7Fzp0fn9M2/YDssTQ9uC4PDp/zhGP4K0z0FSmVDMlmmx3Pmfv66mmCA5KMCK9Ugg8aZvLUn+tyv5bIGkpBlFP9NnHkH+jQWm1TaA1Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752585578; c=relaxed/simple; bh=43RqOH0vDyP4We00MaWJduNehIjGYYlIcpxYMQwmDgo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SQ9MQVqYmigVxOTTH9vpYJJVhdm3jqoGHCTflDnzwQxcwvT4eUmo7RJCTO/xrIkDyEVWqrUKdcC4Pejg6F2/U2lu2iQTlysdnFidmFoPfVNvzEsB1LhMh5Yn6XLkOuZK7jP2Ymhx3JRg0ki199rgBzkU9EPrV0NefTkdkkee/IM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WFqMUUOD; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="WFqMUUOD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A8F5C4CEE3; Tue, 15 Jul 2025 13:19:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1752585577; bh=43RqOH0vDyP4We00MaWJduNehIjGYYlIcpxYMQwmDgo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WFqMUUODL24Mmv8dH64OpGefe3WlTHtzcU/Xnm5afNQY3evXML2MTrH5hgAsE90uA TZ4UWsGK4l3jR6qsOd1K4IFZQVqjVHfVMF1RrEKhZqhTJ54TllquiQ26+q1OjHd66d r4eBdBMIkSSXJ11ExKYLn54kv9phnimMBT91ueWM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Harry Yoo , kernel test robot , Suren Baghdasaryan , Raghavendra K T , Casey Chen , David Wang <00107082@163.com>, Kent Overstreet , Yuanyuan Zhong , Andrew Morton Subject: [PATCH 6.12 093/163] lib/alloc_tag: do not acquire non-existent lock in alloc_tag_top_users() Date: Tue, 15 Jul 2025 15:12:41 +0200 Message-ID: <20250715130812.602175056@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250715130808.777350091@linuxfoundation.org> References: <20250715130808.777350091@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Harry Yoo commit 99af22cd34688cc0d535a1919e0bea4cbc6c1ea1 upstream. alloc_tag_top_users() attempts to lock alloc_tag_cttype->mod_lock even when the alloc_tag_cttype is not allocated because: 1) alloc tagging is disabled because mem profiling is disabled (!alloc_tag_cttype) 2) alloc tagging is enabled, but not yet initialized (!alloc_tag_cttype) 3) alloc tagging is enabled, but failed initialization (!alloc_tag_cttype or IS_ERR(alloc_tag_cttype)) In all cases, alloc_tag_cttype is not allocated, and therefore alloc_tag_top_users() should not attempt to acquire the semaphore. This leads to a crash on memory allocation failure by attempting to acquire a non-existent semaphore: Oops: general protection fault, probably for non-canonical address 0xdffffc000000001b: 0000 [#3] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x00000000000000d8-0x00000000000000df] CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G D 6.16.0-rc2 #1 VOLUNTARY Tainted: [D]=DIE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:down_read_trylock+0xaa/0x3b0 Code: d0 7c 08 84 d2 0f 85 a0 02 00 00 8b 0d df 31 dd 04 85 c9 75 29 48 b8 00 00 00 00 00 fc ff df 48 8d 6b 68 48 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 88 02 00 00 48 3b 5b 68 0f 85 53 01 00 00 65 ff RSP: 0000:ffff8881002ce9b8 EFLAGS: 00010016 RAX: dffffc0000000000 RBX: 0000000000000070 RCX: 0000000000000000 RDX: 000000000000001b RSI: 000000000000000a RDI: 0000000000000070 RBP: 00000000000000d8 R08: 0000000000000001 R09: ffffed107dde49d1 R10: ffff8883eef24e8b R11: ffff8881002cec20 R12: 1ffff11020059d37 R13: 00000000003fff7b R14: ffff8881002cec20 R15: dffffc0000000000 FS: 00007f963f21d940(0000) GS:ffff888458ca6000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f963f5edf71 CR3: 000000010672c000 CR4: 0000000000350ef0 Call Trace: codetag_trylock_module_list+0xd/0x20 alloc_tag_top_users+0x369/0x4b0 __show_mem+0x1cd/0x6e0 warn_alloc+0x2b1/0x390 __alloc_frozen_pages_noprof+0x12b9/0x21a0 alloc_pages_mpol+0x135/0x3e0 alloc_slab_page+0x82/0xe0 new_slab+0x212/0x240 ___slab_alloc+0x82a/0xe00 As David Wang points out, this issue became easier to trigger after commit 780138b12381 ("alloc_tag: check mem_profiling_support in alloc_tag_init"). Before the commit, the issue occurred only when it failed to allocate and initialize alloc_tag_cttype or if a memory allocation fails before alloc_tag_init() is called. After the commit, it can be easily triggered when memory profiling is compiled but disabled at boot. To properly determine whether alloc_tag_init() has been called and its data structures initialized, verify that alloc_tag_cttype is a valid pointer before acquiring the semaphore. If the variable is NULL or an error value, it has not been properly initialized. In such a case, just skip and do not attempt to acquire the semaphore. [harry.yoo@oracle.com: v3] Link: https://lkml.kernel.org/r/20250624072513.84219-1-harry.yoo@oracle.com Link: https://lkml.kernel.org/r/20250620195305.1115151-1-harry.yoo@oracle.com Fixes: 780138b12381 ("alloc_tag: check mem_profiling_support in alloc_tag_init") Fixes: 1438d349d16b ("lib: add memory allocations report in show_mem()") Signed-off-by: Harry Yoo Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202506181351.bba867dd-lkp@intel.com Acked-by: Suren Baghdasaryan Tested-by: Raghavendra K T Cc: Casey Chen Cc: David Wang <00107082@163.com> Cc: Kent Overstreet Cc: Yuanyuan Zhong Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- lib/alloc_tag.c | 3 +++ 1 file changed, 3 insertions(+) --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -113,6 +113,9 @@ size_t alloc_tag_top_users(struct codeta struct codetag_bytes n; unsigned int i, nr = 0; + if (IS_ERR_OR_NULL(alloc_tag_cttype)) + return 0; + if (can_sleep) codetag_lock_module_list(alloc_tag_cttype, true); else if (!codetag_trylock_module_list(alloc_tag_cttype))