From eadde287a62e66b2f9e62d007c59a8f50d4b8413 Mon Sep 17 00:00:00 2001 From: Jamie Hill-Daniel Date: Tue, 18 Jan 2022 08:06:04 +0100 Subject: [PATCH] vfs: fs_context: fix up param length parsing in legacy_parse_param commit 722d94847de29310e8aa03fcbdb41fc92c521756 upstream. The "PAGE_SIZE - 2 - size" calculation in legacy_parse_param() is an unsigned type so a large value of "size" results in a high positive value instead of a negative value as expected. Fix this by getting rid of the subtraction. Signed-off-by: Jamie Hill-Daniel Signed-off-by: William Liu Tested-by: Salvatore Bonaccorso Tested-by: Thadeu Lima de Souza Cascardo Acked-by: Dan Carpenter Acked-by: Al Viro Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/fs_context.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/fs_context.c b/fs/fs_context.c index 2834d1afa6e8..b11677802ee1 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -530,7 +530,7 @@ static int legacy_parse_param(struct fs_context *fc, struct fs_parameter *param) param->key); } - if (len > PAGE_SIZE - 2 - size) + if (size + len + 2 > PAGE_SIZE) return invalf(fc, "VFS: Legacy: Cumulative options too large"); if (strchr(param->key, ',') || (param->type == fs_value_is_string &&