{"id":"AZL-52969","summary":"CVE-2024-49885 affecting package kernel 6.6.126.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm, slub: avoid zeroing kmalloc redzone\n\nSince commit 946fa0dbf2d8 (\"mm/slub: extend redzone check to extra\nallocated kmalloc space than requested\"), setting orig_size treats\nthe wasted space (object_size - orig_size) as a redzone. However with\ninit_on_free=1 we clear the full object-\u003esize, including the redzone.\n\nAdditionally we clear the object metadata, including the stored orig_size,\nmaking it zero, which makes check_object() treat the whole object as a\nredzone.\n\nThese issues lead to the following BUG report with \"slub_debug=FUZ\ninit_on_free=1\":\n\n[    0.000000] =============================================================================\n[    0.000000] BUG kmalloc-8 (Not tainted): kmalloc Redzone overwritten\n[    0.000000] -----------------------------------------------------------------------------\n[    0.000000]\n[    0.000000] 0xffff000010032858-0xffff00001003285f @offset=2136. First byte 0x0 instead of 0xcc\n[    0.000000] FIX kmalloc-8: Restoring kmalloc Redzone 0xffff000010032858-0xffff00001003285f=0xcc\n[    0.000000] Slab 0xfffffdffc0400c80 objects=36 used=23 fp=0xffff000010032a18 flags=0x3fffe0000000200(workingset|node=0|zone=0|lastcpupid=0x1ffff)\n[    0.000000] Object 0xffff000010032858 @offset=2136 fp=0xffff0000100328c8\n[    0.000000]\n[    0.000000] Redzone  ffff000010032850: cc cc cc cc cc cc cc cc                          ........\n[    0.000000] Object   ffff000010032858: cc cc cc cc cc cc cc cc                          ........\n[    0.000000] Redzone  ffff000010032860: cc cc cc cc cc cc cc cc                          ........\n[    0.000000] Padding  ffff0000100328b4: 00 00 00 00 00 00 00 00 00 00 00 00              ............\n[    0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc3-next-20240814-00004-g61844c55c3f4 #144\n[    0.000000] Hardware name: NXP i.MX95 19X19 board (DT)\n[    0.000000] Call trace:\n[    0.000000]  dump_backtrace+0x90/0xe8\n[    0.000000]  show_stack+0x18/0x24\n[    0.000000]  dump_stack_lvl+0x74/0x8c\n[    0.000000]  dump_stack+0x18/0x24\n[    0.000000]  print_trailer+0x150/0x218\n[    0.000000]  check_object+0xe4/0x454\n[    0.000000]  free_to_partial_list+0x2f8/0x5ec\n\nTo address the issue, use orig_size to clear the used area. And restore\nthe value of orig_size after clear the remaining area.\n\nWhen CONFIG_SLUB_DEBUG not defined, (get_orig_size()' directly returns\ns-\u003eobject_size. So when using memset to init the area, the size can simply\nbe orig_size, as orig_size returns object_size when CONFIG_SLUB_DEBUG not\nenabled. And orig_size can never be bigger than object_size.","modified":"2026-04-01T05:17:55.559471Z","published":"2024-10-21T18:15:11Z","upstream":["CVE-2024-49885"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-49885"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.126.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-52969.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}