Re: [arm] BUG: KASAN: slab-out-of-bounds in memcmp+0x30/0x5c

From: Arnd Bergmann
Date: Tue Nov 17 2020 - 10:26:57 EST

On Tue, Nov 17, 2020 at 3:44 PM Naresh Kamboju
<naresh.kamboju@xxxxxxxxxx> wrote:
>
> While booting arm KASAN config enabled kernel on TI x15 device
> Linux version 5.10.0-rc3-next-20201116.
>
> The reported issue is not a regression since we have recently started testing
> arm+kasan builds on LKFT.
>
> The boot was not successful on x15 and qemu_arm for some other reason.
> The kernel config and crash log attached to this email.

Nice find!

> [ 13.071906] BUG: KASAN: slab-out-of-bounds in memcmp+0x30/0x5c
> [ 13.077526] Synopsys Designware Multimedia Card Interface Driver
> [ 13.077781] Read of size 1 at addr c5ae1d90 by task kworker/0:0/5
> [ 13.089918]
> [ 13.091433] CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted
> 5.10.0-rc3-next-20201116 #2
> [ 13.093605] sdhci-pltfm: SDHCI platform and OF driver helper
> [ 13.099135] Hardware name: Generic DRA74X (Flattened Device Tree)
> [ 13.110942] Workqueue: events dbs_work_handler
> [ 13.115442] [<c0315abc>] (unwind_backtrace) from [<c030ebf8>]
> (show_stack+0x10/0x14)
> [ 13.123240] [<c030ebf8>] (show_stack) from [<c16c91cc>]
> (dump_stack+0xc8/0xe0)
> [ 13.130518] [<c16c91cc>] (dump_stack) from [<c051b4ec>]
> (print_address_description.constprop.0+0x34/0x2dc)
> [ 13.140238] [<c051b4ec>] (print_address_description.constprop.0)
> from [<c051b9e0>] (kasan_report+0x1a8/0x1c4)
> [ 13.145871] omap_gpio 4805d000.gpio: Could not set line 27 debounce
> to 200000 microseconds (-22)
> [ 13.150221] [<c051b9e0>] (kasan_report) from [<c0997704>] (memcmp+0x30/0x5c)
> [ 13.159064] sdhci-omap 4809c000.mmc: Got CD GPIO
> [ 13.166123] [<c0997704>] (memcmp) from [<c0c33694>]
> (ti_abb_set_voltage_sel+0x94/0x58c)
> [ 13.166150] [<c0c33694>] (ti_abb_set_voltage_sel) from [<c0c0f0f8>]
> (_regulator_call_set_voltage_sel+0xd8/0x12c)


I see this code in ti_abb_set_voltage_sel():

if (sel >= desc->n_voltages) {
dev_err(dev, "%s: sel idx(%d) >= n_voltages(%d)\n", __func__,
sel, desc->n_voltages);
return -EINVAL;
}

/* If we are in the same index as we were, nothing to do here! */
if (sel == abb->current_info_idx) {
dev_dbg(dev, "%s: Already at sel=%d\n", __func__, sel);
return ret;
}

/* If data is exactly the same, then just update index, no change */
info = &abb->info[sel];
oinfo = &abb->info[abb->current_info_idx];
if (!memcmp(info, oinfo, sizeof(*info))) {

One of the two pointers overflows the abb->info array that is allocated
with length 'desc->n_voltages'. The 'sel' argument is checked against
that limit, so I assume it's abb->current_info_idx, and this is indeed
initialized as

/* We do not know where the OPP voltage is at the moment */
abb->current_info_idx = -EINVAL;

Using the negative '-EINVAL' as an array index would indeed cause
an out-of-bounds access.

Could you try adding this extra bounds check?

index 3e60bff76194..c475a9461027 100644
--- a/drivers/regulator/ti-abb-regulator.c
+++ b/drivers/regulator/ti-abb-regulator.c
@@ -345,7 +345,8 @@ static int ti_abb_set_voltage_sel(struct
regulator_dev *rdev, unsigned sel)
/* If data is exactly the same, then just update index, no change */
info = &abb->info[sel];
oinfo = &abb->info[abb->current_info_idx];
- if (!memcmp(info, oinfo, sizeof(*info))) {
+ if (abb->current_info_idx >= 0 &&
+ !memcmp(info, oinfo, sizeof(*info))) {
dev_dbg(dev, "%s: Same data new idx=%d, old idx=%d\n", __func__,
sel, abb->current_info_idx);
goto out;

Arnd

(rest of the report below)

> [ 13.173027] sdhci-omap 4809c000.mmc: supply vqmmc not found, using
> dummy regulator
> [ 13.178825] [<c0c0f0f8>] (_regulator_call_set_voltage_sel) from
> [<c0c0f654>] (_regulator_do_set_voltage+0x508/0x644)
> [ 13.207208] [<c0c0f654>] (_regulator_do_set_voltage) from
> [<c0c18558>] (regulator_set_voltage_rdev+0xc4/0x2fc)
> [ 13.217276] [<c0c18558>] (regulator_set_voltage_rdev) from
> [<c0c14928>] (regulator_do_balance_voltage+0x304/0x658)
> [ 13.227692] [<c0c14928>] (regulator_do_balance_voltage) from
> [<c0c1839c>] (regulator_set_voltage_unlocked+0x1ac/0x2a4)
> [ 13.238455] [<c0c1839c>] (regulator_set_voltage_unlocked) from
> [<c0c18834>] (regulator_set_voltage+0xa4/0xfc)
> [ 13.248437] [<c0c18834>] (regulator_set_voltage) from [<c1316458>]
> (_opp_set_voltage+0x8c/0x13c)
> [ 13.257283] [<c1316458>] (_opp_set_voltage) from [<c13167ac>]
> (ti_opp_supply_set_opp+0x2a4/0x330)
> [ 13.266216] [<c13167ac>] (ti_opp_supply_set_opp) from [<c1311a98>]
> (dev_pm_opp_set_rate+0x274/0x7cc)
> [ 13.275411] [<c1311a98>] (dev_pm_opp_set_rate) from [<c13188b8>]
> (__cpufreq_driver_target+0x2fc/0x8fc)
> [ 13.284779] [<c13188b8>] (__cpufreq_driver_target) from
> [<c131dfac>] (od_dbs_update+0x22c/0x294)
> [ 13.293623] [<c131dfac>] (od_dbs_update) from [<c131f484>]
> (dbs_work_handler+0x44/0x88)
> [ 13.301683] [<c131f484>] (dbs_work_handler) from [<c038159c>]
> (process_one_work+0x410/0x7ac)
> [ 13.310174] [<c038159c>] (process_one_work) from [<c0381998>]
> (worker_thread+0x60/0x8d0)
> [ 13.318320] [<c0381998>] (worker_thread) from [<c038c2d4>]
> (kthread+0x258/0x268)
> [ 13.325769] [<c038c2d4>] (kthread) from [<c03001b0>]
> (ret_from_fork+0x14/0x24)
> [ 13.333031] Exception stack(0xc3937fb0 to 0xc3937ff8)
> [ 13.338117] 7fa0: 00000000
> 00000000 00000000 00000000
> [ 13.346346] 7fc0: 00000000 00000000 00000000 00000000 00000000
> 00000000 00000000 00000000
> [ 13.354573] 7fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> [ 13.361223]
> [ 13.362729] Allocated by task 1:
> [ 13.365987] ____kasan_kmalloc.constprop.0+0x90/0xa4
> [ 13.370986] __kmalloc_track_caller+0x184/0x5e0
> [ 13.375550] devres_alloc_node+0x24/0x64
> [ 13.379507] __devm_ioremap+0x2c/0xac
> [ 13.383194] __devm_ioremap_resource+0xe8/0x1b8
> [ 13.387758] ti_abb_probe+0x298/0xeb4
> [ 13.391447] platform_drv_probe+0x60/0xb8
> [ 13.395490] really_probe+0x170/0x70c
> [ 13.399182] driver_probe_device+0x94/0x254
> [ 13.403394] device_driver_attach+0x84/0x8c
> [ 13.407608] __driver_attach+0xd4/0x18c
> [ 13.411471] bus_for_each_dev+0xf0/0x144
> [ 13.415424] bus_add_driver+0x248/0x2dc
> [ 13.419289] driver_register+0xcc/0x1a0
> [ 13.423151] do_one_initcall+0xb4/0x248
> [ 13.427019] kernel_init_freeable+0x1ec/0x244
> [ 13.431409] kernel_init+0x8/0x128
> [ 13.434836] ret_from_fork+0x14/0x24
> [ 13.438434] 0x0
> [ 13.440286]
> [ 13.441793] The buggy address belongs to the object at c5ae1d00
> [ 13.441793] which belongs to the cache kmalloc-128 of size 128
> [ 13.453682] The buggy address is located 16 bytes to the right of
> [ 13.453682] 128-byte region [c5ae1d00, c5ae1d80)
> [ 13.464516] The buggy address belongs to the page:
> [ 13.469343] page:52ce07bb refcount:1 mapcount:0 mapping:00000000
> index:0x0 pfn:0x85ae1
> [ 13.477304] flags: 0x200(slab)
> [ 13.480392] raw: 00000200 00000100 00000122 c3801d00 00000000
> 00100010 ffffffff 00000001
> [ 13.488526] raw: 00000000
> [ 13.491163] page dumped because: kasan: bad access detected
> [ 13.496764]
> [ 13.498266] Memory state around the buggy address:
> [ 13.503086] c5ae1c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 13.509652] c5ae1d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [ 13.516218] >c5ae1d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 13.522780] ^
> [ 13.525855] c5ae1e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [ 13.532422] c5ae1e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 13.538983] ==================================================================
> [ 13.546242] Disabling lock debugging due to kernel taint
>
>
> full test log link,
> https://lkft.validation.linaro.org/scheduler/job/1944986#L2188
>
> metadata:
> git branch: master
> git repo: https://gitlab.com/Linaro/lkft/mirrors/next/linux-next
> git describe: next-20201116
> make_kernelversion: 5.10.0-rc3
> kernel-config: https://builds.tuxbuild.com/1kMYEMmo35DocMgHZ9AtJReL3rN/config
>
>
> --
> Linaro LKFT
> https://lkft.linaro.org