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| author | Ronnie Sahlberg <lsahlber@redhat.com> | 2018-12-13 08:06:16 +1000 |
|---|---|---|
| committer | Steve French <stfrench@microsoft.com> | 2018-12-23 22:41:31 -0600 |
| commit | 59a63e479ce36a3f24444c3a36efe82b78e4a8e0 (patch) | |
| tree | f7c1c07ac295014a01fa1d2bc8a4dff0156076e3 /fs/cifs/readdir.c | |
| parent | 52baa51d30573273341b78a3e3ed0d9a845d3e55 (diff) | |
| download | lwn-59a63e479ce36a3f24444c3a36efe82b78e4a8e0.tar.gz lwn-59a63e479ce36a3f24444c3a36efe82b78e4a8e0.zip | |
cifs: check ntwrk_buf_start for NULL before dereferencing it
RHBZ: 1021460
There is an issue where when multiple threads open/close the same directory
ntwrk_buf_start might end up being NULL, causing the call to smbCalcSize
later to oops with a NULL deref.
The real bug is why this happens and why this can become NULL for an
open cfile, which should not be allowed.
This patch tries to avoid a oops until the time when we fix the underlying
issue.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/cifs/readdir.c')
| -rw-r--r-- | fs/cifs/readdir.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c index e169e1a5fd35..3925a7bfc74d 100644 --- a/fs/cifs/readdir.c +++ b/fs/cifs/readdir.c @@ -655,7 +655,14 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos, /* scan and find it */ int i; char *cur_ent; - char *end_of_smb = cfile->srch_inf.ntwrk_buf_start + + char *end_of_smb; + + if (cfile->srch_inf.ntwrk_buf_start == NULL) { + cifs_dbg(VFS, "ntwrk_buf_start is NULL during readdir\n"); + return -EIO; + } + + end_of_smb = cfile->srch_inf.ntwrk_buf_start + server->ops->calc_smb_size( cfile->srch_inf.ntwrk_buf_start, server); |