6.12-stable patches

added patches:
	mm-mmap-fix-__mmap_region-error-handling-in-rare-merge-failure-case.patch

diff --git a/queue-6.12/mm-mmap-fix-__mmap_region-error-handling-in-rare-merge-failure-case.patch b/queue-6.12/mm-mmap-fix-__mmap_region-error-handling-in-rare-merge-failure-case.patch
new file mode 100644 (file)
index 0000000..40df1c1
--- /dev/null
+++ b/queue-6.12/mm-mmap-fix-__mmap_region-error-handling-in-rare-merge-failure-case.patch
@@ -0,0 +1,80 @@
+From Liam.Howlett@oracle.com  Wed Nov 20 13:30:17 2024
+From: "Liam R. Howlett" <Liam.Howlett@oracle.com>
+Date: Tue, 19 Nov 2024 12:59:45 -0500
+Subject: mm/mmap: fix __mmap_region() error handling in rare merge failure case
+To: stable@vger.kernel.org
+Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, Lorenzo Stoakes <lorenzo.stoakes@oracle.com>, Jann Horn <jannh@google.com>, "Liam R. Howlett" <Liam.Howlett@Oracle.com>, syzbot+bc6bfc25a68b7a020ee1@syzkaller.appspotmail.com, Vlastimil Babka <vbabka@suse.cz>
+Message-ID: <20241119175945.2600945-1-Liam.Howlett@oracle.com>
+
+From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>
+
+The mmap_region() function tries to install a new vma, which requires a
+pre-allocation for the maple tree write due to the complex locking
+scenarios involved.
+
+Recent efforts to simplify the error recovery required the relocation of
+the preallocation of the maple tree nodes (via vma_iter_prealloc()
+calling mas_preallocate()) higher in the function.
+
+The relocation of the preallocation meant that, if there was a file
+associated with the vma and the driver call (mmap_file()) modified the
+vma flags, then a new merge of the new vma with existing vmas is
+attempted.
+
+During the attempt to merge the existing vma with the new vma, the vma
+iterator is used - the same iterator that would be used for the next
+write attempt to the tree.  In the event of needing a further allocation
+and if the new allocations fails, the vma iterator (and contained maple
+state) will cleaned up, including freeing all previous allocations and
+will be reset internally.
+
+Upon returning to the __mmap_region() function, the error is available
+in the vma_merge_struct and can be used to detect the -ENOMEM status.
+
+Hitting an -ENOMEM scenario after the driver callback leaves the system
+in a state that undoing the mapping is worse than continuing by dipping
+into the reserve.
+
+A preallocation should be performed in the case of an -ENOMEM and the
+allocations were lost during the failure scenario.  The __GFP_NOFAIL
+flag is used in the allocation to ensure the allocation succeeds after
+implicitly telling the driver that the mapping was happening.
+
+The range is already set in the vma_iter_store() call below, so it is
+not necessary and is dropped.
+
+Reported-by: syzbot+bc6bfc25a68b7a020ee1@syzkaller.appspotmail.com
+Closes: https://syzkaller.appspot.com/x/log.txt?x=17b0ace8580000
+Fixes: 5de195060b2e2 ("mm: resolve faulty mmap_region() error path behaviour")
+Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
+Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
+Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
+Cc: Jann Horn <jannh@google.com>
+Cc: <stable@vger.kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ mm/mmap.c |   13 ++++++++++++-
+ 1 file changed, 12 insertions(+), 1 deletion(-)
+
+--- a/mm/mmap.c
++++ b/mm/mmap.c
+@@ -1491,7 +1491,18 @@ static unsigned long __mmap_region(struc
+                               vm_flags = vma->vm_flags;
+                               goto file_expanded;
+                       }
+-                      vma_iter_config(&vmi, addr, end);
++
++                      /*
++                       * In the unlikely even that more memory was needed, but
++                       * not available for the vma merge, the vma iterator
++                       * will have no memory reserved for the write we told
++                       * the driver was happening.  To keep up the ruse,
++                       * ensure the allocation for the store succeeds.
++                       */
++                      if (vmg_nomem(&vmg)) {
++                              mas_preallocate(&vmi.mas, vma,
++                                              GFP_KERNEL|__GFP_NOFAIL);
++                      }
+               }
+ 
+               vm_flags = vma->vm_flags;

diff --git a/queue-6.12/series b/queue-6.12/series
index 750d7e62ab850571080f35233353516c261ec47b..d68b99c712cc75f9145269a7aba40a807e407aff 100644 (file)
--- a/queue-6.12/series
+++ b/queue-6.12/series
@@ -1,2 +1,3 @@
 hv_sock-initializing-vsk-trans-to-null-to-prevent-a-dangling-pointer.patch
 media-uvcvideo-skip-parsing-frames-of-type-uvc_vs_undefined-in-uvc_parse_format.patch
+mm-mmap-fix-__mmap_region-error-handling-in-rare-merge-failure-case.patch