Re: [PATCH v1] regmap-irq: Fix out-of-bounds access when allocating config buffers

[Amit Pundir]

On Wed, 12 Jul 2023 at 01:01, Isaac J. Manjarres
<isaacmanjarres@xxxxxxxxxx> wrote:
>
> When allocating the 2D array for handling IRQ type registers in
> regmap_add_irq_chip_fwnode(), the intent is to allocate a matrix
> with num_config_bases rows and num_config_regs columns.
>
> This is currently handled by allocating a buffer to hold a pointer for
> each row (i.e. num_config_bases). After that, the logic attempts to
> allocate the memory required to hold the register configuration for
> each row. However, instead of doing this allocation for each row
> (i.e. num_config_bases allocations), the logic erroneously does this
> allocation num_config_regs number of times.
>
> This scenario can lead to out-of-bounds accesses when num_config_regs
> is greater than num_config_bases. Fix this by updating the terminating
> condition of the loop that allocates the memory for holding the register
> configuration to allocate memory only for each row in the matrix.
>
> Amit Pundir reported a crash that was occurring on his db845c device
> due to memory corruption (see "Closes" tag for Amit's report). The KASAN
> report below helped narrow it down to this issue:

Tested-by: Amit Pundir <amit.pundir@xxxxxxxxxx> # tested on Dragonboard 845c

>
> [   14.033877][    T1] ==================================================================
> [   14.042507][    T1] BUG: KASAN: invalid-access in regmap_add_irq_chip_fwnode+0x594/0x1364
> [   14.050796][    T1] Write of size 8 at addr 06ffff8081021850 by task init/1
> [   14.057841][    T1] Pointer tag: [06], memory tag: [fe]
> [   14.063124][    T1]
> [   14.065349][    T1] CPU: 2 PID: 1 Comm: init Tainted: G        W   E      6.4.0-mainline-g6a4b67fef3e2 #1
> [   14.075014][    T1] Hardware name: Thundercomm Dragonboard 845c (DT)
> [   14.081432][    T1] Call trace:
> [   14.084618][    T1]  dump_backtrace+0xe8/0x108
> [   14.089144][    T1]  show_stack+0x18/0x30
> [   14.093215][    T1]  dump_stack_lvl+0x50/0x6c
> [   14.097642][    T1]  print_report+0x178/0x4c0
> [   14.102070][    T1]  kasan_report+0xd4/0x12c
> [   14.106407][    T1]  kasan_tag_mismatch+0x28/0x40
> [   14.111178][    T1]  __hwasan_tag_mismatch+0x2c/0x5c
> [   14.116222][    T1]  regmap_add_irq_chip_fwnode+0x594/0x1364
> [   14.121961][    T1]  devm_regmap_add_irq_chip+0xb8/0x144
> [   14.127346][    T1]  wcd934x_slim_status+0x210/0x28c [wcd934x]
> [   14.133307][    T1]  slim_device_alloc_laddr+0x1ac/0x1ec [slimbus]
> [   14.139669][    T1]  slim_device_probe+0x80/0x124 [slimbus]
> [   14.145394][    T1]  really_probe+0x250/0x4d8
> [   14.149826][    T1]  __driver_probe_device+0x104/0x1ac
> [   14.155041][    T1]  driver_probe_device+0x80/0x218
> [   14.159990][    T1]  __driver_attach+0x19c/0x2e4
> [   14.164678][    T1]  bus_for_each_dev+0x158/0x1b4
> [   14.169454][    T1]  driver_attach+0x34/0x44
> [   14.173790][    T1]  bus_add_driver+0x1fc/0x328
> [   14.178390][    T1]  driver_register+0xdc/0x1b4
> [   14.182995][    T1]  __slim_driver_register+0x6c/0x84 [slimbus]
> [   14.189068][    T1]  init_module+0x20/0xfe4 [wcd934x]
> [   14.194219][    T1]  do_one_initcall+0x110/0x418
> [   14.198916][    T1]  do_init_module+0x124/0x30c
> [   14.203521][    T1]  load_module+0x1938/0x1ab0
> [   14.208034][    T1]  __arm64_sys_finit_module+0x110/0x138
> [   14.213509][    T1]  invoke_syscall+0x70/0x170
> [   14.218015][    T1]  el0_svc_common+0xf0/0x138
> [   14.222523][    T1]  do_el0_svc+0x40/0xb8
> [   14.226596][    T1]  el0_svc+0x2c/0x78
> [   14.230405][    T1]  el0t_64_sync_handler+0x68/0xb4
> [   14.235354][    T1]  el0t_64_sync+0x19c/0x1a0
> [   14.239778][    T1]
> [   14.242004][    T1] The buggy address belongs to the object at ffffff8081021850
> [   14.242004][    T1]  which belongs to the cache kmalloc-8 of size 8
> [   14.255669][    T1] The buggy address is located 0 bytes inside of
> [   14.255669][    T1]  8-byte region [ffffff8081021850, ffffff8081021858)
> [   14.255685][    T1]
> [   14.255689][    T1] The buggy address belongs to the physical page:
> [   14.255699][    T1] page:0000000080887a30 refcount:1 mapcount:0 mapping:0000000000000000 index:0x85ffff8081021ee0 pfn:0x101021
> [   14.275062][    T1] flags: 0x4000000000000200(slab|zone=1|kasantag=0x0)
> [   14.275078][    T1] page_type: 0xffffffff()
> [   14.275091][    T1] raw: 4000000000000200 49ffff8080002200 dead000000000122 0000000000000000
> [   14.275103][    T1] raw: 85ffff8081021ee0 00000000810000ea 00000001ffffffff 0000000000000000
> [   14.275110][    T1] page dumped because: kasan: bad access detected
> [   14.275116][    T1]
> [   14.275119][    T1] Memory state around the buggy address:
> [   14.275125][    T1]  ffffff8081021600: fe fe fe 9a fe fe 5b 3c fe fe c9 fe b4 3f fe 54
> [   14.275133][    T1]  ffffff8081021700: fe fe ad 6b fe fe fe 87 fe fe 39 c9 fe 03 fe ea
> [   14.275143][    T1] >ffffff8081021800: fe fe e1 fe 06 fe fe 21 fe fe e7 fe de fe fe 70
> [   14.275149][    T1]                                   ^
> [   14.371674][    T1]  ffffff8081021900: d7 fe fe 87 fe a0 fe fe fe 80 e0 f0 05 fe fe fe
> [   14.379667][    T1]  ffffff8081021a00: 94 fe 31 fe fe e5 c8 00 d0 fe a1 fe fe e2 e5 fe
> [   14.387664][    T1] ==================================================================
>
> Fixes: faa87ce9196d ("regmap-irq: Introduce config registers for irq types")
> Reported-by: Amit Pundir <amit.pundir@xxxxxxxxxx>
> Closes: https://lore.kernel.org/all/CAMi1Hd04mu6JojT3y6wyN2YeVkPR5R3qnkKJ8iR8if_YByCn4w@xxxxxxxxxxxxxx/
> Tested-by: John Stultz <jstultz@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # v6.0+
> Cc: Aidan MacDonald <aidanmacdonald.0x0@xxxxxxxxx>
> Cc: Saravana Kannan <saravanak@xxxxxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Signed-off-by: Isaac J. Manjarres <isaacmanjarres@xxxxxxxxxx>
> ---
>  drivers/base/regmap/regmap-irq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/base/regmap/regmap-irq.c b/drivers/base/regmap/regmap-irq.c
> index ced0dcf86e0b..45fd13ef13fc 100644
> --- a/drivers/base/regmap/regmap-irq.c
> +++ b/drivers/base/regmap/regmap-irq.c
> @@ -717,7 +717,7 @@ int regmap_add_irq_chip_fwnode(struct fwnode_handle *fwnode,
>                 if (!d->config_buf)
>                         goto err_alloc;
>
> -               for (i = 0; i < chip->num_config_regs; i++) {
> +               for (i = 0; i < chip->num_config_bases; i++) {
>                         d->config_buf[i] = kcalloc(chip->num_config_regs,
>                                                    sizeof(**d->config_buf),
>                                                    GFP_KERNEL);
> --
> 2.41.0.255.g8b1d071c50-goog
>