On Tue, 2021-05-18 at 18:55:03 UTC, Jon Hunter wrote:
> 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
> ...
> [<c029bb1c>] (___cache_free) from [<c029c658>] (kfree+0xac/0x1bc)
> [<c029c658>] (kfree) from [<c06da094>] (mtd_otp_size+0xc4/0x108)
> [<c06da094>] (mtd_otp_size) from [<c06dc864>] (mtd_device_parse_register+0xe4/0x2b4)
> [<c06dc864>] (mtd_device_parse_register) from [<c06e3ccc>] (spi_nor_probe+0x210/0x2c0)
> [<c06e3ccc>] (spi_nor_probe) from [<c06e9578>] (spi_probe+0x88/0xac)
> [<c06e9578>] (spi_probe) from [<c066891c>] (really_probe+0x214/0x3a4)
> [<c066891c>] (really_probe) from [<c0668b14>] (driver_probe_device+0x68/0xc0)
> [<c0668b14>] (driver_probe_device) from [<c0666cf8>] (bus_for_each_drv+0x5c/0xbc)
> [<c0666cf8>] (bus_for_each_drv) from [<c0668694>] (__device_attach+0xe4/0x150)
> [<c0668694>] (__device_attach) from [<c06679e0>] (bus_probe_device+0x84/0x8c)
> [<c06679e0>] (bus_probe_device) from [<c06657f8>] (device_add+0x48c/0x868)
> [<c06657f8>] (device_add) from [<c06eb784>] (spi_add_device+0xa0/0x168)
> [<c06eb784>] (spi_add_device) from [<c06ec9a8>] (spi_register_controller+0x8b8/0xb38)
> [<c06ec9a8>] (spi_register_controller) from [<c06ecc3c>] (devm_spi_register_controller+0x14/0x50)
> [<c06ecc3c>] (devm_spi_register_controller) from [<c06f0510>] (tegra_spi_probe+0x33c/0x450)
> [<c06f0510>] (tegra_spi_probe) from [<c066abec>] (platform_probe+0x5c/0xb8)
> [<c066abec>] (platform_probe) from [<c066891c>] (really_probe+0x214/0x3a4)
> [<c066891c>] (really_probe) from [<c0668b14>] (driver_probe_device+0x68/0xc0)
> [<c0668b14>] (driver_probe_device) from [<c0668e30>] (device_driver_attach+0x58/0x60)
> [<c0668e30>] (device_driver_attach) from [<c0668eb8>] (__driver_attach+0x80/0xc8)
> [<c0668eb8>] (__driver_attach) from [<c0666c48>] (bus_for_each_dev+0x78/0xb8)
> [<c0666c48>] (bus_for_each_dev) from [<c0667c44>] (bus_add_driver+0x164/0x1e8)
> [<c0667c44>] (bus_add_driver) from [<c066997c>] (driver_register+0x7c/0x114)
> [<c066997c>] (driver_register) from [<c010223c>] (do_one_initcall+0x50/0x2b0)
> [<c010223c>] (do_one_initcall) from [<c11011f0>] (kernel_init_freeable+0x1a8/0x1fc)
> [<c11011f0>] (kernel_init_freeable) from [<c0c09190>] (kernel_init+0x8/0x118)
> [<c0c09190>] (kernel_init) from [<c01001b0>] (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 <jonathanh@xxxxxxxxxx>
> Reviewed-by: Michael Walle <michael@xxxxxxxx>
Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.
Miquel
