Liam R. Howlett 64c37e134b kernel: be more careful about dup_mmap() failures and uprobe registering ... If a memory allocation fails during dup_mmap(), the maple tree can be left in an unsafe state for other iterators besides the exit path. All the locks are dropped before the exit_mmap() call (in mm/mmap.c), but the incomplete mm_struct can be reached through (at least) the rmap finding the vmas which have a pointer back to the mm_struct. Up to this point, there have been no issues with being able to find an mm_struct that was only partially initialised. Syzbot was able to make the incomplete mm_struct fail with recent forking changes, so it has been proven unsafe to use the mm_struct that hasn't been initialised, as referenced in the link below. Although 8ac662f5da ("fork: avoid inappropriate uprobe access to invalid mm") fixed the uprobe access, it does not completely remove the race. This patch sets the MMF_OOM_SKIP to avoid the iteration of the vmas on the oom side (even though this is extremely unlikely to be selected as an oom victim in the race window), and sets MMF_UNSTABLE to avoid other potential users from using a partially initialised mm_struct. When registering vmas for uprobe, skip the vmas in an mm that is marked unstable. Modifying a vma in an unstable mm may cause issues if the mm isn't fully initialised. Link: https://lore.kernel.org/all/6756d273.050a0220.2477f.003d.GAE@google.com/ Link: https://lkml.kernel.org/r/20250127170221.1761366-1-Liam.Howlett@oracle.com Fixes: d240629148 ("fork: use __mt_dup() to duplicate maple tree in dup_mmap()") Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Jann Horn <jannh@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Peng Zhang <zhangpeng.00@bytedance.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>		2025-02-01 03:53:25 -08:00
..
Makefile	perf/hw_breakpoint: Add KUnit test for constraints accounting	2022-08-30 10:56:20 +02:00
callchain.c	sysctl: treewide: constify the ctl_table argument of proc_handlers	2024-07-24 20:59:29 +02:00
core.c	perf: map pages in advance	2025-01-10 18:16:50 +01:00
hw_breakpoint.c	perf/hw_breakpoint: use ERR_PTR_PCPU(), IS_ERR_PCPU() and PTR_ERR_PCPU() macros	2024-11-05 17:12:32 -08:00
hw_breakpoint_test.c	perf/hw_breakpoint: remove MODULE_LICENSE in non-modules	2023-04-13 13:13:52 -07:00
internal.h	perf/core: Add aux_pause, aux_resume, aux_start_paused	2024-11-05 12:55:43 +01:00
ring_buffer.c	perf: map pages in advance	2025-01-10 18:16:50 +01:00
uprobes.c	kernel: be more careful about dup_mmap() failures and uprobe registering	2025-02-01 03:53:25 -08:00