{"id":"DEBIAN-CVE-2024-49885","details":"In the Linux kernel, the following vulnerability has been resolved:  mm, slub: avoid zeroing kmalloc redzone  Since commit 946fa0dbf2d8 (\"mm/slub: extend redzone check to extra allocated kmalloc space than requested\"), setting orig_size treats the wasted space (object_size - orig_size) as a redzone. However with init_on_free=1 we clear the full object-\u003esize, including the redzone.  Additionally we clear the object metadata, including the stored orig_size, making it zero, which makes check_object() treat the whole object as a redzone.  These issues lead to the following BUG report with \"slub_debug=FUZ init_on_free=1\":  [    0.000000] ============================================================================= [    0.000000] BUG kmalloc-8 (Not tainted): kmalloc Redzone overwritten [    0.000000] ----------------------------------------------------------------------------- [    0.000000] [    0.000000] 0xffff000010032858-0xffff00001003285f @offset=2136. First byte 0x0 instead of 0xcc [    0.000000] FIX kmalloc-8: Restoring kmalloc Redzone 0xffff000010032858-0xffff00001003285f=0xcc [    0.000000] Slab 0xfffffdffc0400c80 objects=36 used=23 fp=0xffff000010032a18 flags=0x3fffe0000000200(workingset|node=0|zone=0|lastcpupid=0x1ffff) [    0.000000] Object 0xffff000010032858 @offset=2136 fp=0xffff0000100328c8 [    0.000000] [    0.000000] Redzone  ffff000010032850: cc cc cc cc cc cc cc cc                          ........ [    0.000000] Object   ffff000010032858: cc cc cc cc cc cc cc cc                          ........ [    0.000000] Redzone  ffff000010032860: cc cc cc cc cc cc cc cc                          ........ [    0.000000] Padding  ffff0000100328b4: 00 00 00 00 00 00 00 00 00 00 00 00              ............ [    0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc3-next-20240814-00004-g61844c55c3f4 #144 [    0.000000] Hardware name: NXP i.MX95 19X19 board (DT) [    0.000000] Call trace: [    0.000000]  dump_backtrace+0x90/0xe8 [    0.000000]  show_stack+0x18/0x24 [    0.000000]  dump_stack_lvl+0x74/0x8c [    0.000000]  dump_stack+0x18/0x24 [    0.000000]  print_trailer+0x150/0x218 [    0.000000]  check_object+0xe4/0x454 [    0.000000]  free_to_partial_list+0x2f8/0x5ec  To address the issue, use orig_size to clear the used area. And restore the value of orig_size after clear the remaining area.  When CONFIG_SLUB_DEBUG not defined, (get_orig_size()' directly returns s-\u003eobject_size. So when using memset to init the area, the size can simply be orig_size, as orig_size returns object_size when CONFIG_SLUB_DEBUG not enabled. And orig_size can never be bigger than object_size.","modified":"2026-09-15T09:03:12.358259574Z","published":"2024-10-21T18:15:11.230Z","upstream":["CVE-2024-49885"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2024-49885"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.11.4-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-49885.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.11.4-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-49885.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}