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udf: Fix NULL pointer dereference in udf_symlink function 

In function udf_symlink, epos.bh is assigned with the value returned
by udf_tgetblk. The function udf_tgetblk is defined in udf/misc.c
and returns the value of sb_getblk function that could be NULL.
Then, epos.bh is used without any check, causing a possible
NULL pointer dereference when sb_getblk fails.

This fix adds a check to validate the value of epos.bh.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=213083
Signed-off-by: Arturo Giusti <koredump@protonmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Arturo Giusti 2021-05-18 12:34:57 +02:00 committed by Jan Kara
parent a149127be5
commit fa236c2b2d
1 changed files with 4 additions and 0 deletions
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4
fs/udf/namei.c
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@ -934,6 +934,10 @@ static int udf_symlink(struct user_namespace *mnt_userns, struct inode *dir,
iinfo->i_location.partitionReferenceNum, iinfo->i_location.partitionReferenceNum,
0); 0);
epos.bh = udf_tgetblk(sb, block); epos.bh = udf_tgetblk(sb, block);
if (unlikely(!epos.bh)) {
err = -ENOMEM;
goto out_no_entry;
}
lock_buffer(epos.bh); lock_buffer(epos.bh);
memset(epos.bh->b_data, 0x00, bsize); memset(epos.bh->b_data, 0x00, bsize);
set_buffer_uptodate(epos.bh); set_buffer_uptodate(epos.bh);