From bc8e157fdb466536557b97b6c0df6d7b46a2b91b Mon Sep 17 00:00:00 2001 From: Jon Hunter Date: Tue, 18 May 2021 19:55:03 +0100 Subject: [PATCH] mtd: core: Fix freeing of otp_info buffer Commit 4b361cfa8624 ("mtd: core: add OTP nvmem provider support") is causing the following panic ... ------------[ cut here ]------------ kernel BUG at /local/workdir/tegra/linux_next/kernel/mm/slab.c:2730! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM Modules linked in: CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc2-next-20210518 #1 Hardware name: NVIDIA Tegra SoC (Flattened Device Tree) PC is at ___cache_free+0x3f8/0x51c ... [] (___cache_free) from [] (kfree+0xac/0x1bc) [] (kfree) from [] (mtd_otp_size+0xc4/0x108) [] (mtd_otp_size) from [] (mtd_device_parse_register+0xe4/0x2b4) [] (mtd_device_parse_register) from [] (spi_nor_probe+0x210/0x2c0) [] (spi_nor_probe) from [] (spi_probe+0x88/0xac) [] (spi_probe) from [] (really_probe+0x214/0x3a4) [] (really_probe) from [] (driver_probe_device+0x68/0xc0) [] (driver_probe_device) from [] (bus_for_each_drv+0x5c/0xbc) [] (bus_for_each_drv) from [] (__device_attach+0xe4/0x150) [] (__device_attach) from [] (bus_probe_device+0x84/0x8c) [] (bus_probe_device) from [] (device_add+0x48c/0x868) [] (device_add) from [] (spi_add_device+0xa0/0x168) [] (spi_add_device) from [] (spi_register_controller+0x8b8/0xb38) [] (spi_register_controller) from [] (devm_spi_register_controller+0x14/0x50) [] (devm_spi_register_controller) from [] (tegra_spi_probe+0x33c/0x450) [] (tegra_spi_probe) from [] (platform_probe+0x5c/0xb8) [] (platform_probe) from [] (really_probe+0x214/0x3a4) [] (really_probe) from [] (driver_probe_device+0x68/0xc0) [] (driver_probe_device) from [] (device_driver_attach+0x58/0x60) [] (device_driver_attach) from [] (__driver_attach+0x80/0xc8) [] (__driver_attach) from [] (bus_for_each_dev+0x78/0xb8) [] (bus_for_each_dev) from [] (bus_add_driver+0x164/0x1e8) [] (bus_add_driver) from [] (driver_register+0x7c/0x114) [] (driver_register) from [] (do_one_initcall+0x50/0x2b0) [] (do_one_initcall) from [] (kernel_init_freeable+0x1a8/0x1fc) [] (kernel_init_freeable) from [] (kernel_init+0x8/0x118) [] (kernel_init) from [] (ret_from_fork+0x14/0x24) ... ---[ end trace 0f652dd222de75d7 ]--- In the function mtd_otp_size() a buffer is allocated by calling kmalloc() and a pointer to the buffer is stored in a variable 'info'. The pointer 'info' may then be incremented depending on the length returned from mtd_get_user/fact_prot_info(). If 'info' is incremented, when kfree() is called to free the buffer the above panic occurs because we are no longer passing the original address of the buffer allocated. Fix this by indexing through the buffer allocated to avoid incrementing the pointer. Fixes: 4b361cfa8624 ("mtd: core: add OTP nvmem provider support") Signed-off-by: Jon Hunter Reviewed-by: Michael Walle Signed-off-by: Miquel Raynal Link: https://lore.kernel.org/linux-mtd/20210518185503.162787-1-jonathanh@nvidia.com --- drivers/mtd/mtdcore.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 3ae2616..ffa46cc 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -792,10 +792,8 @@ static ssize_t mtd_otp_size(struct mtd_info *mtd, bool is_user) if (ret) goto err; - for (i = 0; i < retlen / sizeof(*info); i++) { - size += info->length; - info++; - } + for (i = 0; i < retlen / sizeof(*info); i++) + size += info[i].length; kfree(info); return size; -- 2.7.4