Commit f9f0a539 authored by Piotr Zalewski's avatar Piotr Zalewski Committed by Kent Overstreet
Browse files

bcachefs: Change OPT_STR max to be 1 less than the size of choices array 



Change OPT_STR max value to be 1 less than the "ARRAY_SIZE" of "_choices"
array. As a result, remove -1 from (opt->max-1) in bch2_opt_to_text.

The "_choices" array is a null-terminated array, so computing the maximum
using "ARRAY_SIZE" without subtracting 1 yields an incorrect result. Since
bch2_opt_validate don't subtract 1, as bch2_opt_to_text does, values
bigger than the actual maximum would pass through option validation.

Reported-by: default avatar <syzbot+bee87a0c3291c06aa8c6@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=bee87a0c3291c06aa8c6


Fixes: 63c4b254 ("bcachefs: Better superblock opt validation")
Suggested-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: default avatarPiotr Zalewski <pZ010001011111@proton.me>
Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent baefd3f8

fs/bcachefs/opts.c

+2 −2
Original line number Diff line number Diff line
@@ -226,7 +226,7 @@ const struct bch_option bch2_opt_table[] = { 
#define OPT_UINT(_min, _max)	.type = BCH_OPT_UINT,			\

				.min = _min, .max = _max

#define OPT_STR(_choices)	.type = BCH_OPT_STR,			\

				.min = 0, .max = ARRAY_SIZE(_choices),	\

				.min = 0, .max = ARRAY_SIZE(_choices) - 1, \

				.choices = _choices

#define OPT_STR_NOLIMIT(_choices)	.type = BCH_OPT_STR,		\

				.min = 0, .max = U64_MAX,		\
@@ -428,7 +428,7 @@ void bch2_opt_to_text(struct printbuf *out, 
			prt_printf(out, "%lli", v);

		break;

	case BCH_OPT_STR:

		if (v < opt->min || v >= opt->max - 1)

		if (v < opt->min || v >= opt->max)

			prt_printf(out, "(invalid option %lli)", v);

		else if (flags & OPT_SHOW_FULL_LIST)

			prt_string_option(out, opt->choices, v);