57 lines
2.0 KiB
Diff
57 lines
2.0 KiB
Diff
From: Randy Dunlap <rdunlap@infradead.org>
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Date: Wed, 1 Apr 2020 21:10:58 -0700
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Subject: mm: mempolicy: require at least one nodeid for MPOL_PREFERRED
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Origin: https://git.kernel.org/linus/aa9f7d5172fac9bf1f09e678c35e287a40a7b7dd
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Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2020-11565
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Using an empty (malformed) nodelist that is not caught during mount option
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parsing leads to a stack-out-of-bounds access.
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The option string that was used was: "mpol=prefer:,". However,
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MPOL_PREFERRED requires a single node number, which is not being provided
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here.
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Add a check that 'nodes' is not empty after parsing for MPOL_PREFERRED's
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nodeid.
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Fixes: 095f1fc4ebf3 ("mempolicy: rework shmem mpol parsing and display")
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Reported-by: Entropy Moe <3ntr0py1337@gmail.com>
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Reported-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com
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Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Tested-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com
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Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
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Link: http://lkml.kernel.org/r/89526377-7eb6-b662-e1d8-4430928abde9@infradead.org
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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---
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mm/mempolicy.c | 6 +++++-
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1 file changed, 5 insertions(+), 1 deletion(-)
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diff --git a/mm/mempolicy.c b/mm/mempolicy.c
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index 460683bbe58c..5fb427aed612 100644
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--- a/mm/mempolicy.c
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+++ b/mm/mempolicy.c
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@@ -2898,7 +2898,9 @@ int mpol_parse_str(char *str, struct mempolicy **mpol)
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switch (mode) {
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case MPOL_PREFERRED:
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/*
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- * Insist on a nodelist of one node only
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+ * Insist on a nodelist of one node only, although later
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+ * we use first_node(nodes) to grab a single node, so here
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+ * nodelist (or nodes) cannot be empty.
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*/
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if (nodelist) {
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char *rest = nodelist;
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@@ -2906,6 +2908,8 @@ int mpol_parse_str(char *str, struct mempolicy **mpol)
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rest++;
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if (*rest)
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goto out;
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+ if (nodes_empty(nodes))
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+ goto out;
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}
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break;
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case MPOL_INTERLEAVE:
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--
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2.26.2
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