Re: [PATCH v2 1/8] unicode: Fix utf8_load() error path

From: Theodore Ts'o
Date: Tue Sep 03 2024 - 07:41:23 EST


On Mon, Sep 02, 2024 at 07:55:03PM -0300, André Almeida wrote:
> utf8_load() requests the symbol "utf8_data_table" and then checks if the
> requested UTF-8 version is supported. If it's unsupported, it tries to
> put the data table using symbol_put(). If an unsupported version is
> requested, symbol_put() fails like this:
>
> kernel BUG at kernel/module/main.c:786!
> RIP: 0010:__symbol_put+0x93/0xb0
> Call Trace:
> <TASK>
> ? __die_body.cold+0x19/0x27
> ? die+0x2e/0x50
> ? do_trap+0xca/0x110
> ? do_error_trap+0x65/0x80
> ? __symbol_put+0x93/0xb0
> ? exc_invalid_op+0x51/0x70
> ? __symbol_put+0x93/0xb0
> ? asm_exc_invalid_op+0x1a/0x20
> ? __pfx_cmp_name+0x10/0x10
> ? __symbol_put+0x93/0xb0
> ? __symbol_put+0x62/0xb0
> utf8_load+0xf8/0x150
>
> That happens because symbol_put() expects the unique string that
> identify the symbol, instead of a pointer to the loaded symbol. Fix that
> by using such string.
>
> Fixes: 2b3d04787012 ("unicode: Add utf8-data module")
> Signed-off-by: André Almeida <andrealmeid@xxxxxxxxxx>

Nice catch!

Reviewed-by: Theodore Ts'o <tytso@xxxxxxx>