Messages in this thread Patch in this message | | | From | "Zhijian Li (Fujitsu)" <> | Subject | Re: [PATCH 1/2] firewire: Kill unnecessary buf check in device_attribute.show | Date | Mon, 18 Mar 2024 06:24:52 +0000 |
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On 18/03/2024 12:46, Takashi Sakamoto wrote: > Hi, > > On Mon, Jan 22, 2024 at 05:56:04PM +0900, Takashi Sakamoto wrote: >> Hi, >> >> On Mon, Jan 22, 2024 at 01:39:41PM +0800, Li Zhijian wrote: >>> Per Documentation/filesystems/sysfs.rst: >>>> sysfs allocates a buffer of size (PAGE_SIZE) and passes it to the >>>> method. >>> >>> So we can kill the unnecessary buf check safely. >>> >>> Signed-off-by: Li Zhijian <lizhijian@fujitsu.com> >>> --- >>> drivers/firewire/core-device.c | 14 +++----------- >>> 1 file changed, 3 insertions(+), 11 deletions(-) >> >> Applied both patches to linux-next branch, since they are not so-urgent >> fixes. > > I realized that it causes an issue at the path to initialize device > structure for node in IEEE 1394 bus. > > (drivers/firewire/core-device.c) > fw_device_init() / fw_device_refresh() > ->create_units() > ->init_fw_attribute_group() > ->attr->show(dev, attr, NULL) > > kernel: ------------[ cut here ]------------ > kernel: invalid sysfs_emit: buf:0000000000000000 > kernel: WARNING: CPU: 5 PID: 647501 at fs/sysfs/file.c:747 sysfs_emit+0xb5/0xc0 > kernel: Modules linked in: snd_fireworks(OE) snd_firewire_lib(OE) firewire_ohci(OE) firewire_core(OE) cfg80211 veth nft_masq crc_itu_t vfio_pci vfio_pci_core vfio_iommu_type1 vfio iommufd rpcsec_gss_krb5 nfsv4 nfs netfs snd_seq_dummy sn> > kernel: crypto_simd asus_wmi snd_timer ledtrig_audio cryptd cec sparse_keymap nls_iso8859_1 rapl platform_profile wmi_bmof k10temp i2c_piix4 snd rc_core i2c_algo_bit ccp soundcore zfs(PO) spl(O) input_leds joydev cdc_mbim cdc_wdm mac_h> > kernel: CPU: 5 PID: 647501 Comm: kworker/5:0 Tainted: P W OE 6.8.0-11-generic #11-Ubuntu > kernel: Hardware name: System manufacturer System Product Name/TUF GAMING X570-PLUS, BIOS 5003 10/07/2023 > kernel: Workqueue: firewire fw_device_workfn [firewire_core] > kernel: RIP: 0010:sysfs_emit+0xb5/0xc0 > kernel: Code: 25 28 00 00 00 75 29 c9 31 d2 31 c9 31 f6 31 ff 45 31 c0 45 31 c9 e9 5a 89 c7 00 48 89 fe 48 c7 c7 64 06 3f bd e8 1b 80 b4 ff <0f> 0b 31 c0 eb c7 e8 a0 ea c5 00 90 90 90 90 90 90 90 90 90 90 90 > kernel: RSP: 0018:ffffacd857103cd0 EFLAGS: 00010246 > kernel: RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > kernel: RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > kernel: RBP: ffffacd857103d20 R08: 0000000000000000 R09: 0000000000000000 > kernel: R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000010000 > kernel: R13: ffffffffc28e2ff8 R14: 0000000000000000 R15: 0000000000000001 > kernel: FS: 0000000000000000(0000) GS:ffff918190080000(0000) knlGS:0000000000000000 > kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > kernel: CR2: 00007835dca0b048 CR3: 00000003cb898000 CR4: 00000000003506f0 > kernel: Call Trace: > kernel: <TASK> > kernel: ? show_regs+0x6d/0x80 > kernel: ? __warn+0x89/0x160 > kernel: ? sysfs_emit+0xb5/0xc0 > kernel: ? report_bug+0x17e/0x1b0 > kernel: ? handle_bug+0x51/0xa0 > kernel: ? exc_invalid_op+0x18/0x80 > kernel: ? asm_exc_invalid_op+0x1b/0x20 > kernel: ? sysfs_emit+0xb5/0xc0 > kernel: show_immediate+0x13f/0x1d0 [firewire_core] > kernel: init_fw_attribute_group+0x81/0x150 [firewire_core] > kernel: create_units+0x119/0x160 [firewire_core] > kernel: fw_device_init+0x1a9/0x330 [firewire_core] > kernel: fw_device_workfn+0x12/0x20 [firewire_core] > kernel: process_one_work+0x16f/0x350 > kernel: worker_thread+0x306/0x440 > kernel: ? __pfx_worker_thread+0x10/0x10 > kernel: kthread+0xf2/0x120 > kernel: ? __pfx_kthread+0x10/0x10 > kernel: ret_from_fork+0x47/0x70 > kernel: ? __pfx_kthread+0x10/0x10 > kernel: ret_from_fork_asm+0x1b/0x30 > kernel: </TASK> > kernel: ---[ end trace 0000000000000000 ]--- > kernel: ------------[ cut here ]------------ > > Furthermore, 'show_text_leaf()' returns negative value when the NULL > pointer is passed. It results in the lack of vendor/model names from > sysfs. > > I absolutely overlooked them. I would like to fix them within this merge > window, or revert them as a last resort... >
Sorry for the mistake. I haven't considered callers from other than sysfs. I'm fine to reverting both *two*.
If we are interesting in the sysfs_emit conversion one, i cooked(see the attachment) a patch to revert "firewire: Kill unnecessary buf check in device_attribute.show" only.
(Feel free to ignore it if you have had a local fix.)
Thanks Zhijian
> > Regards > > Takashi SakamotoFrom 96ad3e15b86e2504f3c17fd6a10be48e5ff81cb1 Mon Sep 17 00:00:00 2001 From: Li Zhijian <lizhijian@fujitsu.com> Date: Mon, 18 Mar 2024 14:05:32 +0800 Subject: [PATCH] Revert "firewire: Kill unnecessary buf check in device_attribute.show"
This reverts commit 4a2b06ca33763b363038d333274e212db6ff0de1.
The previous fix didn't consider callers from other than sysfs. Revert it to fix the NULL dereference
kernel: ? sysfs_emit+0xb5/0xc0 kernel: show_immediate+0x13f/0x1d0 [firewire_core] kernel: init_fw_attribute_group+0x81/0x150 [firewire_core] kernel: create_units+0x119/0x160 [firewire_core] kernel: fw_device_init+0x1a9/0x330 [firewire_core] kernel: fw_device_workfn+0x12/0x20 [firewire_core] kernel: process_one_work+0x16f/0x350 kernel: worker_thread+0x306/0x440 kernel: ? __pfx_worker_thread+0x10/0x10 kernel: kthread+0xf2/0x120 kernel: ? __pfx_kthread+0x10/0x10 kernel: ret_from_fork+0x47/0x70 kernel: ? __pfx_kthread+0x10/0x10 kernel: ret_from_fork_asm+0x1b/0x30 kernel: </TASK> kernel: ---[ end trace 0000000000000000 ]--- kernel: ------------[ cut here ]------------
Fixes: 4a2b06ca3376 ("firewire: Kill unnecessary buf check in device_attribute.show") Reported-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Li Zhijian <lizhijian@fujitsu.com> --- drivers/firewire/core-device.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c index c0976f6268d3..f208a02d0ebf 100644 --- a/drivers/firewire/core-device.c +++ b/drivers/firewire/core-device.c @@ -322,7 +322,7 @@ static ssize_t show_immediate(struct device *dev, if (value < 0) return -ENOENT; - return sysfs_emit(buf, "0x%06x\n", value); + return buf ? sysfs_emit(buf, "0x%06x\n", value) : 0; } #define IMMEDIATE_ATTR(name, key) \ @@ -334,6 +334,8 @@ static ssize_t show_text_leaf(struct device *dev, struct config_rom_attribute *attr = container_of(dattr, struct config_rom_attribute, attr); const u32 *directories[] = {NULL, NULL}; + size_t bufsize; + char dummy_buf[2]; int i, ret = -ENOENT; down_read(&fw_device_rwsem); @@ -355,9 +357,15 @@ static ssize_t show_text_leaf(struct device *dev, } } + if (buf) { + bufsize = PAGE_SIZE - 1; + } else { + buf = dummy_buf; + bufsize = 1; + } + for (i = 0; i < ARRAY_SIZE(directories) && !!directories[i]; ++i) { - int result = fw_csr_string(directories[i], attr->key, buf, - PAGE_SIZE - 1); + int result = fw_csr_string(directories[i], attr->key, buf, bufsize); // Detected. if (result >= 0) { ret = result; @@ -366,7 +374,7 @@ static ssize_t show_text_leaf(struct device *dev, // in the root directory follows to the directory entry for vendor ID // instead of the immediate value for vendor ID. result = fw_csr_string(directories[i], CSR_DIRECTORY | attr->key, buf, - PAGE_SIZE - 1); + bufsize); if (result >= 0) ret = result; } -- 2.29.2
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