From: Mihai Moldovan ionic@ionic.de
[ Upstream commit 8c94b430b9f6213dec84e309bb480a71778c4213 ]
If the user selects the very first entry in a page and performs a search-up operation, or selects the very last entry in a page and performs a search-down operation that will not succeed (e.g., via [/]asdfzzz[Up Arrow]), nconf will never terminate searching the page.
The reason is that in this case, the starting point will be set to -1 or n, which is then translated into (n - 1) (i.e., the last entry of the page) or 0 (i.e., the first entry of the page) and finally the search begins. This continues to work fine until the index reaches 0 or (n - 1), at which point it will be decremented to -1 or incremented to n, but not checked against the starting point right away. Instead, it's wrapped around to the bottom or top again, after which the starting point check occurs... and naturally fails.
My original implementation added another check for -1 before wrapping the running index variable around, but Masahiro Yamada pointed out that the actual issue is that the comparison point (starting point) exceeds bounds (i.e., the [0,n-1] interval) in the first place and that, instead, the starting point should be fixed.
This has the welcome side-effect of also fixing the case where the starting point was n while searching down, which also lead to an infinite loop.
OTOH, this code is now essentially all his work.
Amazingly, nobody seems to have been hit by this for 11 years - or at the very least nobody bothered to debug and fix this.
Signed-off-by: Mihai Moldovan ionic@ionic.de Signed-off-by: Masahiro Yamada masahiroy@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- scripts/kconfig/nconf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/scripts/kconfig/nconf.c b/scripts/kconfig/nconf.c index f7049e288e93..c58a46904861 100644 --- a/scripts/kconfig/nconf.c +++ b/scripts/kconfig/nconf.c @@ -502,8 +502,8 @@ static int get_mext_match(const char *match_str, match_f flag) else if (flag == FIND_NEXT_MATCH_UP) --match_start;
+ match_start = (match_start + items_num) % items_num; index = match_start; - index = (index + items_num) % items_num; while (true) { char *str = k_menu_items[index].str; if (strcasestr(str, match_str) != 0)