Messages in this thread | | | Subject | Re: [PATCH] ipmi: use dynamic memory for DMI driver override | From | Corey Minyard <> | Date | Mon, 22 Jan 2018 07:46:15 -0600 |
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On 01/17/2018 11:06 AM, John Garry wrote: > On 17/01/2018 16:49, Corey Minyard wrote: >> On 01/17/2018 10:36 AM, John Garry wrote: >>> Currently a crash can be seen if we reach the "err" >>> label in dmi_add_platform_ipmi(), calling >>> platform_device_put(), like here: >>> [ 7.270584] (null): ipmi:dmi: Unable to add resources: -16 >>> [ 7.330229] ------------[ cut here ]------------ >>> [ 7.334889] kernel BUG at mm/slub.c:3894! >>> [ 7.338936] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP >>> [ 7.344475] Modules linked in: >>> [ 7.347556] CPU: 1 PID: 1 Comm: swapper/0 Not tainted >>> 4.15.0-rc2-00004-gbe9cb7b-dirty #114 >>> [ 7.355907] Hardware name: Huawei Taishan 2280 /D05, BIOS Hisilicon >>> D05 IT17 Nemo 2.0 RC0 11/29/2017 >>> [ 7.365137] task: 00000000c211f6d3 task.stack: 00000000f276e9af >>> [ 7.371116] pstate: 60000005 (nZCv daif -PAN -UAO) >>> [ 7.375957] pc : kfree+0x194/0x1b4 >>> [ 7.379389] lr : platform_device_release+0xcc/0xd8 >>> [ 7.384225] sp : ffff0000092dba90 >>> [ 7.387567] x29: ffff0000092dba90 x28: ffff000008a83000 >>> [ 7.392933] x27: ffff0000092dbc10 x26: 00000000000000e6 >>> [ 7.398297] x25: 0000000000000003 x24: ffff0000085b51e8 >>> [ 7.403662] x23: 0000000000000100 x22: ffff7e0000234cc0 >>> [ 7.409027] x21: ffff000008af3660 x20: ffff8017d21acc10 >>> [ 7.414392] x19: ffff8017d21acc00 x18: 0000000000000002 >>> [ 7.419757] x17: 0000000000000001 x16: 0000000000000008 >>> [ 7.425121] x15: 0000000000000001 x14: 6666666678303d65 >>> [ 7.430486] x13: 6469727265766f5f x12: 7265766972642e76 >>> [ 7.435850] x11: 6564703e2d617020 x10: 6530326435373638 >>> [ 7.441215] x9 : 3030303030303030 x8 : 3d76656420657361 >>> [ 7.446580] x7 : ffff000008f59df8 x6 : ffff8017fbe0ea50 >>> [ 7.451945] x5 : 0000000000000000 x4 : 0000000000000000 >>> [ 7.457309] x3 : ffffffffffffffff x2 : 0000000000000000 >>> [ 7.462674] x1 : 0fffc00000000800 x0 : ffff7e0000234ce0 >>> [ 7.468039] Process swapper/0 (pid: 1, stack limit = >>> 0x00000000f276e9af) >>> [ 7.474809] Call trace: >>> [ 7.477272] kfree+0x194/0x1b4 >>> [ 7.480351] platform_device_release+0xcc/0xd8 >>> [ 7.484837] device_release+0x34/0x90 >>> [ 7.488531] kobject_put+0x70/0xcc >>> [ 7.491961] put_device+0x14/0x1c >>> [ 7.495304] platform_device_put+0x14/0x1c >>> [ 7.499439] dmi_add_platform_ipmi+0x348/0x3ac >>> [ 7.503923] scan_for_dmi_ipmi+0xfc/0x10c >>> [ 7.507970] do_one_initcall+0x38/0x124 >>> [ 7.511840] kernel_init_freeable+0x188/0x228 >>> [ 7.516238] kernel_init+0x10/0x100 >>> [ 7.519756] ret_from_fork+0x10/0x18 >>> [ 7.523362] Code: f94002c0 37780080 f94012c0 37000040 (d4210000) >>> [ 7.529552] ---[ end trace 11750e4787deef9e ]--- >>> [ 7.534228] Kernel panic - not syncing: Attempted to kill init! >>> exitcode=0x0000000b >>> [ 7.534228] >>> >>> This is because when the device is released in >>> platform_device_release(), we try to free >>> pdev.driver_override. This is a const string, hence >>> the crash. >>> Fix by using dynamic memory for pdev->driver_override. >>> >>> Signed-off-by: John Garry <john.garry@huawei.com> >> >> Oops, sorry about that. Yes, queued for the next release and 4.14.x. >> >> -corey >> >>> >>> diff --git a/drivers/char/ipmi/ipmi_dmi.c >>> b/drivers/char/ipmi/ipmi_dmi.c >>> index ab78b3b..c5112b1 100644 >>> --- a/drivers/char/ipmi/ipmi_dmi.c >>> +++ b/drivers/char/ipmi/ipmi_dmi.c >>> @@ -106,7 +106,10 @@ static void __init dmi_add_platform_ipmi(unsigned >>> long base_addr, >>> pr_err("ipmi:dmi: Error allocation IPMI platform device\n"); >>> return; >>> } >>> - pdev->driver_override = override; >>> + pdev->driver_override = kasprintf(GFP_KERNEL, "%s", >>> + override); > > It would be simpler to use managed variant (to avoid the kfree()), but > I don't think it's possible until the device probes. >
Actually, I don't think you should do the kfree() in ipmi_si_intf.c. It's done in platform_device_release(), and will cause a double free if done in the IPMI code, unless you set it to NULL. I'm going to add a patch to remove that hunk.
-corey
> John > >>> + if (!pdev->driver_override) >>> + goto err; >>> if (type == IPMI_DMI_TYPE_SSIF) { >>> set_prop_entry(p[pidx++], "i2c-addr", u16, base_addr); >>> diff --git a/drivers/char/ipmi/ipmi_si_intf.c >>> b/drivers/char/ipmi/ipmi_si_intf.c >>> index 779869e..2a19aa8 100644 >>> --- a/drivers/char/ipmi/ipmi_si_intf.c >>> +++ b/drivers/char/ipmi/ipmi_si_intf.c >>> @@ -2426,6 +2426,7 @@ int ipmi_si_remove_by_dev(struct device *dev) >>> { >>> struct smi_info *e; >>> int rv = -ENOENT; >>> + struct platform_device *pdev = to_platform_device(dev); >>> mutex_lock(&smi_infos_lock); >>> list_for_each_entry(e, &smi_infos, link) { >>> @@ -2436,6 +2437,7 @@ int ipmi_si_remove_by_dev(struct device *dev) >>> } >>> } >>> mutex_unlock(&smi_infos_lock); >>> + kfree(pdev->driver_override); >>> return rv; >>> } >> >> >> >> . >> > >
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