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Date:   Tue, 11 Jul 2023 12:30:58 -0700
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Message-ID: <20230711193059.2480971-1-isaacmanjarres@google.com>
Subject: [PATCH v1] regmap-irq: Fix out-of-bounds access when allocating
 config buffers
From:   "Isaac J. Manjarres" <isaacmanjarres@google.com>
To:     Russell King <linux@armlinux.org.uk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Mark Brown <broonie@kernel.org>,
        "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>,
        Saravana Kannan <saravanak@google.com>,
        Tomeu Vizoso <tomeu.vizoso@collabora.com>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Cc:     "Isaac J. Manjarres" <isaacmanjarres@google.com>,
        Amit Pundir <amit.pundir@linaro.org>,
        John Stultz <jstultz@google.com>, stable@vger.kernel.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        kernel-team@android.com,
        Russell King <rmk+kernel@arm.linux.org.uk>,
        linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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:

[   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@linaro.org>
Closes: https://lore.kernel.org/all/CAMi1Hd04mu6JojT3y6wyN2YeVkPR5R3qnkKJ8iR8if_YByCn4w@mail.gmail.com/
Tested-by: John Stultz <jstultz@google.com>
Cc: stable@vger.kernel.org # v6.0+
Cc: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Isaac J. Manjarres <isaacmanjarres@google.com>
---
 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