Blame SOURCES/0240-fs-f2fs-Do-not-read-past-the-end-of-nat-journal-entr.patch

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
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Date: Wed, 6 Apr 2022 18:03:37 +0530
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Subject: [PATCH] fs/f2fs: Do not read past the end of nat journal entries
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A corrupt f2fs file system could specify a nat journal entry count
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that is beyond the maximum NAT_JOURNAL_ENTRIES.
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Check if the specified nat journal entry count before accessing the
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array, and throw an error if it is too large.
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Signed-off-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
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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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(cherry picked from commit a3988cb3f0a108dd67ac127a79a4c8479d23334e)
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---
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 grub-core/fs/f2fs.c | 21 ++++++++++++++-------
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 1 file changed, 14 insertions(+), 7 deletions(-)
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diff --git a/grub-core/fs/f2fs.c b/grub-core/fs/f2fs.c
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index 8a9992ca9e..63702214b0 100644
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--- a/grub-core/fs/f2fs.c
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+++ b/grub-core/fs/f2fs.c
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@@ -632,23 +632,27 @@ get_nat_journal (struct grub_f2fs_data *data)
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   return err;
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 }
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-static grub_uint32_t
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-get_blkaddr_from_nat_journal (struct grub_f2fs_data *data, grub_uint32_t nid)
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+static grub_err_t
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+get_blkaddr_from_nat_journal (struct grub_f2fs_data *data, grub_uint32_t nid,
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+                              grub_uint32_t *blkaddr)
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 {
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   grub_uint16_t n = grub_le_to_cpu16 (data->nat_j.n_nats);
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-  grub_uint32_t blkaddr = 0;
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   grub_uint16_t i;
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+  if (n >= NAT_JOURNAL_ENTRIES)
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+    return grub_error (GRUB_ERR_BAD_FS,
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+                       "invalid number of nat journal entries");
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+
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   for (i = 0; i < n; i++)
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     {
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       if (grub_le_to_cpu32 (data->nat_j.entries[i].nid) == nid)
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         {
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-          blkaddr = grub_le_to_cpu32 (data->nat_j.entries[i].ne.block_addr);
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+          *blkaddr = grub_le_to_cpu32 (data->nat_j.entries[i].ne.block_addr);
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           break;
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         }
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     }
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-  return blkaddr;
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+  return GRUB_ERR_NONE;
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 }
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 static grub_uint32_t
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@@ -656,10 +660,13 @@ get_node_blkaddr (struct grub_f2fs_data *data, grub_uint32_t nid)
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 {
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   struct grub_f2fs_nat_block *nat_block;
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   grub_uint32_t seg_off, block_off, entry_off, block_addr;
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-  grub_uint32_t blkaddr;
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+  grub_uint32_t blkaddr = 0;
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   grub_err_t err;
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-  blkaddr = get_blkaddr_from_nat_journal (data, nid);
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+  err = get_blkaddr_from_nat_journal (data, nid, &blkaddr);
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+  if (err != GRUB_ERR_NONE)
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+    return 0;
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+
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   if (blkaddr)
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     return blkaddr;
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