dcavalca / rpms / grub2

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Daniel Axtens <dja@axtens.net>
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Date: Thu, 21 Jan 2021 18:35:22 +1100
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Subject: [PATCH] disk/lvm: Do not overread metadata
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We could reach the end of valid metadata and not realize, leading to
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some buffer overreads. Check if we have reached the end and bail.
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Signed-off-by: Daniel Axtens <dja@axtens.net>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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---
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 grub-core/disk/lvm.c | 31 +++++++++++++++++++++++++------
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 1 file changed, 25 insertions(+), 6 deletions(-)
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diff --git a/grub-core/disk/lvm.c b/grub-core/disk/lvm.c
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index 03587e744dc..267be7b9536 100644
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--- a/grub-core/disk/lvm.c
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+++ b/grub-core/disk/lvm.c
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@@ -314,17 +314,23 @@ error_parsing_metadata:
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 	  while (1)
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 	    {
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 	      grub_ssize_t s;
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-	      while (grub_isspace (*p))
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+	      while (grub_isspace (*p) && p < mda_end)
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 		p++;
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+	      if (p == mda_end)
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+		goto fail4;
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+
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 	      if (*p == '}')
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 		break;
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 	      pv = grub_zalloc (sizeof (*pv));
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 	      q = p;
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-	      while (*q != ' ')
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+	      while (*q != ' ' && q < mda_end)
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 		q++;
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+	      if (q == mda_end)
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+		goto pvs_fail_noname;
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+
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 	      s = q - p;
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 	      pv->name = grub_malloc (s + 1);
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 	      grub_memcpy (pv->name, p, s);
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@@ -367,6 +373,7 @@ error_parsing_metadata:
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 	      continue;
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 	    pvs_fail:
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 	      grub_free (pv->name);
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+	    pvs_fail_noname:
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 	      grub_free (pv);
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 	      goto fail4;
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 	    }
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@@ -388,18 +395,24 @@ error_parsing_metadata:
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 	      struct grub_diskfilter_segment *seg;
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 	      int is_pvmove;
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-	      while (grub_isspace (*p))
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+	      while (grub_isspace (*p) && p < mda_end)
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 		p++;
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+	      if (p == mda_end)
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+		goto fail4;
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+
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 	      if (*p == '}')
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 		break;
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 	      lv = grub_zalloc (sizeof (*lv));
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 	      q = p;
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-	      while (*q != ' ')
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+	      while (*q != ' ' && q < mda_end)
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 		q++;
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+	      if (q == mda_end)
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+		goto lvs_fail;
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+
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 	      s = q - p;
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 	      lv->name = grub_strndup (p, s);
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 	      if (!lv->name)
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@@ -572,9 +585,12 @@ error_parsing_metadata:
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 			  if (p == NULL)
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 			    goto lvs_segment_fail2;
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 			  q = ++p;
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-			  while (*q != '"')
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+			  while (q < mda_end && *q != '"')
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 			    q++;
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+			  if (q == mda_end)
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+			    goto lvs_segment_fail2;
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+
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 			  s = q - p;
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 			  stripe->name = grub_malloc (s + 1);
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@@ -631,9 +647,12 @@ error_parsing_metadata:
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 			  if (p == NULL)
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 			    goto lvs_segment_fail2;
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 			  q = ++p;
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-			  while (*q != '"')
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+			  while (q < mda_end && *q != '"')
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 			    q++;
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+			  if (q == mda_end)
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+			    goto lvs_segment_fail2;
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+
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 			  s = q - p;
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 			  lvname = grub_malloc (s + 1);