Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

usb: gadget: uac: validate rate list length before storing

UAC1 and UAC2 configfs rate-list attributes parse a comma-separated list of sampling rates and store each parsed value in fixed-size arrays. The arrays have UAC_MAX_RATES entries, but the store paths do not check that the input contains at most that many tokens before writing through opts->name##s[i++].

Writing more than ten rates therefore writes past the end of the p_srates[] or c_srates[] array in struct f_uac1_opts or struct f_uac2_opts.

With CONFIG_UBSAN_BOUNDS enabled, writing an 11-entry rate list to the UAC1 p_srate attribute reports:

UBSAN: array-index-out-of-bounds drivers/usb/gadget/function/f_uac1.c:1669:1 index 10 is out of range for type 'int [10]' __ubsan_handle_out_of_bounds.cold f_uac1_opts_p_srate_store configfs_write_iter vfs_write ksys_write do_syscall_64

The same reproducer against the UAC2 p_srate attribute reports:

UBSAN: array-index-out-of-bounds drivers/usb/gadget/function/f_uac2.c:2087:1 index 10 is out of range for type 'int [10]' __ubsan_handle_out_of_bounds.cold f_uac2_opts_p_srate_store configfs_write_iter vfs_write ksys_write do_syscall_64

Reject additional tokens once UAC_MAX_RATES entries have been parsed. Also keep the original kstrdup() pointer for kfree(), because strsep() advances the parsing cursor. Freeing the advanced cursor leaks the original buffer on successful par…