From: Jamie Hill-Daniel <jamie@hill-daniel.co.uk> mainline inclusion from mainline-v5.17-rc1 commit 722d94847de29310e8aa03fcbdb41fc92c521756 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I4YD3S CVE: CVE-2022-0185 -------------------------------- 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 <jamie@hill-daniel.co.uk> Signed-off-by: William Liu <willsroot@protonmail.com> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Acked-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Luo Meng <luomeng12@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- 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 b7e43a780a62..24ce12f0db32 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -548,7 +548,7 @@ 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 && -- 2.20.1