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 461908C1E for ; Wed, 7 May 2025 01:41:46 +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=1746582106; cv=none; b=MiR0lPYgbshHxod+wqbUsaKd5UVZu2SBtqEfa1Y2MQLf3xtfxPdqpjDIKSBW6uB3XpKotTXZSNjRSG+33NKcrNMXZkChdbkkEEfzKTOQRuOXfT76mv52TYf7aZhznB0J9/WWeVpa9QNC5hxqOkc9g+SqXqNDS6M8G8wymSye4U0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746582106; c=relaxed/simple; bh=9ityg9GGQPQ59OuDk4YgW6K9gKObBHsjxBg0Jv7ROeI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=R0Z0Rxsy2mxkO9Rdo5j4yJCkc7xUGbjlbMHjFciYrwXQoHjHNbwjh92fVsG08S+oso/AMsAiQtxcCwVRdmPHHN/9Dh0CroZX/I8ILkEADL5HCfDz7m/uFIEuXRob7bRIMBecKAHagkT0aoa7JJ3j3q0c7qUsorxkunAagzQvZv4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pR+DDvHq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pR+DDvHq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73028C4CEE4; Wed, 7 May 2025 01:41:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746582106; bh=9ityg9GGQPQ59OuDk4YgW6K9gKObBHsjxBg0Jv7ROeI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pR+DDvHqHTAnvFj2OItmJi7AihRpCBVpQ9e+K3PXggPK+HuN1bjhSE3L7SOTpnQtG 27fpa8YRcjGS5zadSurOIOShFQ41Dw+DXH5lGFGuBr93WT9cLNQkhe9LIq13wm10x0 HDsY4gft1WeCLb6cOkzCV4dAaa/PkyQqyxIfrN9BAGkDySjDxs9l+PiJz7MI8TNu9Z ymAVJuQ1KHCWrerIlAwwtToxho+b0EFD76YW2rKWNwCpRongud+m/iobRLc5hgKHXC qYPtkt50lnL51QpSC3H6MEqBPZxDBNxdpbbYlyK75BIuiJxfiySCEnX0D0c9X2CoLN 4+rkXnniAsCIw== Message-ID: Date: Tue, 6 May 2025 20:41:43 -0500 Precedence: bulk X-Mailing-List: platform-driver-x86@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drivers/platform/x86/amd: pmf: Fix a double free on module unload To: Dan Carpenter Cc: Shyam-sundar.S-k@amd.com, hdegoede@redhat.com, ilpo.jarvinen@linux.intel.com, platform-driver-x86@vger.kernel.org References: <20250506131130.1446262-1-superm1@kernel.org> Content-Language: en-US From: Mario Limonciello In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 5/6/2025 11:11 AM, Mario Limonciello wrote: > On 5/6/2025 10:53 AM, Dan Carpenter wrote: >> On Tue, May 06, 2025 at 08:11:29AM -0500, Mario Limonciello wrote: >>> From: Mario Limonciello >>> >>> If setting up smart PC fails for any reason then this can lead to >>> a double free when unloading amd-pmf.  This is because dev->buf was >>> freed but never set to NULL and is again freed in >>> amd_pmf_deinit_smart_pc(). >>> >>> Explicitly set pointers to NULL after freeing them to avoid the >>> double free. >>> >>> Fixes: 5b1122fc4995f ("platform/x86/amd/pmf: fix cleanup in >>> amd_pmf_init_smart_pc()") >>> Signed-off-by: Mario Limonciello >>> --- >>>   drivers/platform/x86/amd/pmf/tee-if.c | 3 +++ >>>   1 file changed, 3 insertions(+) >>> >>> diff --git a/drivers/platform/x86/amd/pmf/tee-if.c b/drivers/ >>> platform/x86/amd/pmf/tee-if.c >>> index a1e43873a07b0..48902f1c767c6 100644 >>> --- a/drivers/platform/x86/amd/pmf/tee-if.c >>> +++ b/drivers/platform/x86/amd/pmf/tee-if.c >>> @@ -579,10 +579,13 @@ int amd_pmf_init_smart_pc(struct amd_pmf_dev *dev) >>>       amd_pmf_tee_deinit(dev); >>          ^^^^^^^^^^^^^^^^^^^^^^^ >> >>>   err_free_prev_data: >>>       kfree(dev->prev_data); >>> +    dev->prev_data = NULL; >>>   err_free_policy: >>>       kfree(dev->policy_buf); >>> +    dev->policy_buf = NULL; >>>   err_free_dram_buf: >>>       kfree(dev->buf); >>> +    dev->buf = NULL; >>>   err_cancel_work: >>>       cancel_delayed_work_sync(&dev->pb_work); >> >> This is a real bug.  Did you find it from testing or reading the code? > > I found it from testing.  I was testing some other unrelated changes and > found that unloading/reloading the module eventually lead to problems. I > tracked it down to your change. > >> My reading of the code says that this bug can only occur if >> amd_pmf_register_input_device() fails, right? > > No; it was happening from a failure where the system didn't have a > policy or had a "bad" policy. > >> >> We can only call amd_pmf_deinit_smart_pc() if >> amd_pmf_start_policy_engine() >> succeeds because that's where we set: >> >>     dev->smart_pc_enabled = true; >> >> This patch doesn't totally fix the problem because we would still call >> amd_pmf_tee_deinit().  That's why I suspect you found this by auditing >> the code because I think that remaining bug would trigger a stack trace. >> I also worry that there is a small race window where we could trigger >> amd_pmf_tee_deinit() before amd_pmf_init_smart_pc() has finished >> running. >> >> Another bug is that we should cancel the work before freeing all the >> pointers.  This looks like the more serious bug. >> >> What about if we only set dev->smart_pc_enabled = true if the whole >> amd_pmf_init_smart_pc() has succeeded? >> >> regards, >> dan carpenter >> > > Right; it's only set when amd_pmf_start_policy_engine() succeeds which > was not the case for me.  This makes me wonder how exactly this was > happening [amd_pmf_deinit_smart_pc() would only be called from > amd_pmf_deinit_features()]. For completeness; here is the trace back after load/unload which was fixed by this patch I shared (passed through scripts/decode_stacktrace.sh) [ 33.636532] ------------[ cut here ]------------ [ 33.636540] kernel BUG at mm/slub.c:546! [ 33.636554] Oops: invalid opcode: 0000 [#1] SMP NOPTI [ 33.636560] CPU: 4 UID: 0 PID: 3245 Comm: rmmod Not tainted 6.15.0-rc1-00020-g0581d384f344 #79 PREEMPT(full) 4b12a0d175d8a11a0952957398aaf7c2efd0bbd7 [ 33.636565] Hardware name: Framework Laptop 13 (AMD Ryzen AI 300 Series)/FRANMGCP09, BIOS 03.03 03/10/2025 [ 33.636567] RIP: 0010:__slab_free (mm/slub.c:546 (discriminator 1) mm/slub.c:4475 (discriminator 1)) [ 33.636578] Code: 0c 44 0f b6 4c 24 13 44 8b 44 24 14 48 89 44 24 20 49 8b 04 24 4c 8b 54 24 18 48 c1 e8 09 83 e0 01 88 44 24 11 e9 ce fe ff ff <0f> 0b 41 f7 46 08 87 04 00 00 75 91 eb 83 41 f7 46 08 87 04 00 00 All code ======== 0: 0c 44 or $0x44,%al 2: 0f b6 4c 24 13 movzbl 0x13(%rsp),%ecx 7: 44 8b 44 24 14 mov 0x14(%rsp),%r8d c: 48 89 44 24 20 mov %rax,0x20(%rsp) 11: 49 8b 04 24 mov (%r12),%rax 15: 4c 8b 54 24 18 mov 0x18(%rsp),%r10 1a: 48 c1 e8 09 shr $0x9,%rax 1e: 83 e0 01 and $0x1,%eax 21: 88 44 24 11 mov %al,0x11(%rsp) 25: e9 ce fe ff ff jmp 0xfffffffffffffef8 2a:* 0f 0b ud2 <-- trapping instruction 2c: 41 f7 46 08 87 04 00 testl $0x487,0x8(%r14) 33: 00 34: 75 91 jne 0xffffffffffffffc7 36: eb 83 jmp 0xffffffffffffffbb 38: 41 f7 46 08 87 04 00 testl $0x487,0x8(%r14) 3f: 00 Code starting with the faulting instruction =========================================== 0: 0f 0b ud2 2: 41 f7 46 08 87 04 00 testl $0x487,0x8(%r14) 9: 00 a: 75 91 jne 0xffffffffffffff9d c: eb 83 jmp 0xffffffffffffff91 e: 41 f7 46 08 87 04 00 testl $0x487,0x8(%r14) 15: 00 [ 33.636580] RSP: 0018:ffffd3ae43327a10 EFLAGS: 00010246 [ 33.636584] RAX: ffff8a6164a50f00 RBX: 000000008020001e RCX: 0000000000000000 [ 33.636585] RDX: ffffd3ae43327a40 RSI: fffff51cc4929400 RDI: ffffd3ae43327a80 [ 33.636587] RBP: ffffd3ae43327ab0 R08: 0000000000000001 R09: ffffffffaa799600 [ 33.636588] R10: ffff8a6164a50e00 R11: ffffd3ae43327ab0 R12: fffff51cc4929400 [ 33.636589] R13: ffff8a6164a50e00 R14: ffff8a6140042a00 R15: 0000000000000000 [ 33.636590] FS: 00007f6c8ee08680(0000) GS:ffff8a68d20c3000(0000) knlGS:0000000000000000 [ 33.636591] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 33.636592] CR2: 00007f6c8e4578e0 CR3: 000000012fdb0000 CR4: 0000000000b50ef0 [ 33.636594] Call Trace: [ 33.636596] [ 33.636598] ? __call_rcu_common (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-long.h:38 ./include/linux/atomic/atomic-instrumented.h:3189 kernel/rcu/rcu_segcblist.h:52 kernel/rcu/tree.c:2956 kernel/rcu/tree.c:2967 kernel/rcu/tree.c:3106) [ 33.636605] ? platform_remove (drivers/base/platform.c:1424) [ 33.636610] kfree (mm/slub.c:4599 mm/slub.c:4647 mm/slub.c:4845) [ 33.636613] ? mntput_no_expire (fs/namespace.c:259 fs/namespace.c:1492) [ 33.636626] platform_remove (drivers/base/platform.c:1424) [ 33.636628] device_release_driver_internal (drivers/base/dd.c:1275 drivers/base/dd.c:1296) [ 33.636634] driver_detach (drivers/base/dd.c:1360) [ 33.636637] bus_remove_driver (drivers/base/bus.c:748) [ 33.636640] __do_sys_delete_module (kernel/module/main.c:781) [ 33.636646] do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1)) [ 33.636654] ? vfs_read (fs/read_write.c:489 fs/read_write.c:570) [ 33.636658] ? ___pte_offset_map (./include/linux/pgtable.h:347 (discriminator 2) ./include/linux/pgtable.h:624 (discriminator 2) mm/pgtable-generic.c:289 (discriminator 2)) [ 33.636663] ? next_uptodate_folio (./include/linux/xarray.h:1722 mm/filemap.c:3585) [ 33.636668] ? __mod_memcg_lruvec_state (mm/memcontrol.c:586 mm/memcontrol.c:771) [ 33.636673] ? mod_objcg_state (mm/memcontrol.c:2475 mm/memcontrol.c:2837) [ 33.636675] ? xas_load (./include/linux/xarray.h:175 ./include/linux/xarray.h:1264 lib/xarray.c:241) [ 33.636680] ? xa_load (lib/xarray.c:1624) [ 33.636683] ? __memcg_slab_free_hook (mm/memcontrol.c:3093 (discriminator 1)) [ 33.636686] ? __x64_sys_close (fs/open.c:1584 fs/open.c:1566 fs/open.c:1566) [ 33.636689] ? kmem_cache_free (mm/slub.c:4646 (discriminator 1) mm/slub.c:4748 (discriminator 1)) [ 33.636692] ? syscall_exit_to_user_mode (./arch/x86/include/asm/irqflags.h:37 ./arch/x86/include/asm/irqflags.h:114 ./include/linux/entry-common.h:232 kernel/entry/common.c:206 kernel/entry/common.c:218) [ 33.636695] ? do_syscall_64 (arch/x86/entry/syscall_64.c:113) [ 33.636698] ? __count_memcg_events (mm/memcontrol.c:586 mm/memcontrol.c:862) [ 33.636699] ? handle_mm_fault (mm/memory.c:6182 mm/memory.c:6335) [ 33.636704] ? do_user_addr_fault (arch/x86/mm/fault.c:1338) [ 33.636710] ? exc_page_fault (./arch/x86/include/asm/irqflags.h:37 ./arch/x86/include/asm/irqflags.h:114 arch/x86/mm/fault.c:1488 arch/x86/mm/fault.c:1538) [ 33.636713] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) [ 33.636716] RIP: 0033:0x7f6c8e53519b [ 33.636719] Code: 73 01 c3 48 8b 0d 5d bc 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 2d bc 0d 00 f7 d8 64 89 01 48 And this was built and reproduced from platform-x86/review-ilpo-fixes: 0581d384f344e (HEAD, platform-x86/review-ilpo-fixes) platform/x86/amd/hsmp: Make amd_hsmp and hsmp_acpi as mutually exclusive drivers 8e81b9cd6e951 drivers/platform/x86/amd: pmf: Check for invalid Smart PC Policies 690d722e02819 drivers/platform/x86/amd: pmf: Check for invalid sideloaded Smart PC Policies 02c6e43397c39 (tag: platform-drivers-x86-v6.15-4, platform-x86/fixes)