In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ksmbd: reject undersized DACLs before parsing ACEs<\/p>\n
parse_dacl() limits the attacker-controlled ACE count by comparing it
\nwith the number of minimal ACEs that fit in the DACL size. The DACL size
\nfield is 16 bits, but the expression subtracts sizeof(struct smb_acl).
\nBecause sizeof() is unsigned, a DACL size smaller than the ACL header
\nunderflows to a large size_t.<\/p>\n
A malicious client can reach this with:<\/p>\n
SMB2_SET_INFO (InfoType=SMB2_O_INFO_SECURITY)
\n -> smb2_set_info_sec()
\n -> set_info_sec()
\n -> parse_sec_desc()
\n -> parse_dacl()
\n -> init_acl_state(…, 0xffff)
\n -> init_acl_state(…, 0xffff)
\n -> kmalloc_objs(…, 0xffff)<\/p>\n
Thus a malformed security descriptor can make num_aces pass the guard
\nand drive large temporary ACL state and pointer-array allocations.<\/p>\n
Reject DACLs smaller than struct smb_acl before doing the subtraction,
\nso the ACE count check cannot be bypassed by the underflow.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ksmbd: reject undersized DACLs before parsing ACEs<\/p>\n
parse_dacl() limits the attacker-controlled ACE count by comparing it
\nwith the <\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-7027","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/7027","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=7027"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7027"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7027"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}