The patch titled
Subject: fat: fix memory allocation failure handling of match_strdup()
has been added to the -mm tree. Its filename is
fat-fix-memory-allocation-failure-handling-of-match_strdup.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fat-fix-memory-allocation-failure-handling-of-match_strdup.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fat-fix-memory-allocation-failure-handling-of-match_strdup.patch
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------------------------------------------------------
From: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Subject: fat: fix memory allocation failure handling of match_strdup()
In parse_options(), if match_strdup() failed, parse_options() leaves
opts->iocharset in unexpected state (i.e. still pointing the freed
string). And this can be the cause of double free.
To fix, this initialize opts->iocharset always when freeing.
Link: http://lkml.kernel.org/r/8736wp9dzc.fsf@xxxxxxxxxxxxxxxxxx
Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Reported-by: syzbot+90b8e10515ae88228a92@xxxxxxxxxxxxxxxxxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/fat/inode.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)
diff -puN fs/fat/inode.c~fat-fix-memory-allocation-failure-handling-of-match_strdup fs/fat/inode.c
--- a/fs/fat/inode.c~fat-fix-memory-allocation-failure-handling-of-match_strdup
+++ a/fs/fat/inode.c
@@ -707,13 +707,21 @@ static void fat_set_state(struct super_b
brelse(bh);
}
+static void fat_reset_iocharset(struct fat_mount_options *opts)
+{
+ if (opts->iocharset != fat_default_iocharset) {
+ /* Note: opts->iocharset can be NULL here */
+ kfree(opts->iocharset);
+ opts->iocharset = fat_default_iocharset;
+ }
+}
+
static void delayed_free(struct rcu_head *p)
{
struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
unload_nls(sbi->nls_disk);
unload_nls(sbi->nls_io);
- if (sbi->options.iocharset != fat_default_iocharset)
- kfree(sbi->options.iocharset);
+ fat_reset_iocharset(&sbi->options);
kfree(sbi);
}
@@ -1132,7 +1140,7 @@ static int parse_options(struct super_bl
opts->fs_fmask = opts->fs_dmask = current_umask();
opts->allow_utime = -1;
opts->codepage = fat_default_codepage;
- opts->iocharset = fat_default_iocharset;
+ fat_reset_iocharset(opts);
if (is_vfat) {
opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
opts->rodir = 0;
@@ -1289,8 +1297,7 @@ static int parse_options(struct super_bl
/* vfat specific */
case Opt_charset:
- if (opts->iocharset != fat_default_iocharset)
- kfree(opts->iocharset);
+ fat_reset_iocharset(opts);
iocharset = match_strdup(&args[0]);
if (!iocharset)
return -ENOMEM;
@@ -1881,8 +1888,7 @@ out_fail:
iput(fat_inode);
unload_nls(sbi->nls_io);
unload_nls(sbi->nls_disk);
- if (sbi->options.iocharset != fat_default_iocharset)
- kfree(sbi->options.iocharset);
+ fat_reset_iocharset(&sbi->options);
sb->s_fs_info = NULL;
kfree(sbi);
return error;
_
Patches currently in -mm which might be from hirofumi@xxxxxxxxxxxxxxxxxx are
fat-fix-memory-allocation-failure-handling-of-match_strdup.patch
