In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
scsi: megaraid_sas: Limit NVMe request size to the PRP chain frame<\/p>\n
megasas_make_prp_nvme() builds a command’s PRP list in cmd->sg_frame, a
\nDMA pool buffer of instance->max_chain_frame_sz bytes, spending one
\nentry per NVMe page of the transfer plus one per page of the buffer for
\nthe chain pointer. The loop runs until the transfer is described and
\nnever checks the buffer bound.<\/p>\n
max_hw_sectors comes straight from the MDTS the firmware reports for the
\ndrive. On drives with a large MDTS the only thing keeping the list
\ninside the buffer was the block layer default of 1280 KiB, which needs
\n320 entries, which fit into a 4 KiB frame as that holds 512. But since
\ncommit 9b8b84879d4a (“block: Increase BLK_DEF_MAX_SECTORS_CAP”) that
\ndefault is 4 MiB, and such a transfer needs 1025 entries, so the list
\nruns a full page past the end of the frame:<\/p>\n
sd 1:0:1:0: [sdb] tag#630 page boundary ptr_sgl: 0x00000000ba62d13f
\n BUG: unable to handle page fault for address: ff663bcb81e7c000
\n #PF: supervisor write access in kernel mode
\n #PF: error_code(0x0002) – not-present page
\n RIP: 0010:megasas_build_and_issue_cmd_fusion+0xeaa\/0x1870 [megaraid_sas]<\/p>\n
If the page after the frame happens to be mapped, the overrun does not
\nfault but silently corrupts the neighbouring pool entry, which is
\nanother in-flight command’s PRP list.<\/p>\n
Cap max_hw_sectors at what the chain frame can describe, less one page
\nfor transfers that do not start on a page boundary and so need one entry
\nmore. This is the megaraid_sas counterpart of commit 04631f55afc5
\n(“scsi: mpt3sas: Limit NVMe request size to 2 MiB”), but derives the
\nlimit from max_chain_frame_sz rather than hardcoding it.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
scsi: megaraid_sas: Limit NVMe request size to the PRP chain frame<\/p>\n
megasas_make_prp_nvme() builds a command’s PRP list in cmd->sg_<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-24696","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/24696","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=24696"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=24696"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=24696"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}