| Message ID | 20220320135015.19794-1-xiam0nd.tong@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | cifs: fix incorrect use of list iterator after the loop | expand |
On Mon, Mar 21, 2022 at 3:50 PM Xiaomeng Tong <xiam0nd.tong@gmail.com> wrote: > > The bug is here: > if (!tcon) { > resched = true; > list_del_init(&ses->rlist); > cifs_put_smb_ses(ses); > > Because the list_for_each_entry() never exits early (without any > break/goto/return inside the loop), the iterator 'ses' after the > loop will always be an pointer to a invalid struct containing the > HEAD (&pserver->smb_ses_list). As a result, the uses of 'ses' above > will lead to a invalid memory access. > > The original intention should have been to walk each entry 'ses' in > '&tmp_ses_list', delete '&ses->rlist' and put 'ses'. So fix it with > a list_for_each_entry_safe(). > > Fixes: 3663c9045f51a ("cifs: check reconnects for channels of active tcons too") > Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com> > --- > fs/cifs/smb2pdu.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c > index 7e7909b1ae11..f82d6fcb5c64 100644 > --- a/fs/cifs/smb2pdu.c > +++ b/fs/cifs/smb2pdu.c > @@ -3858,8 +3858,10 @@ void smb2_reconnect_server(struct work_struct *work) > tcon = kzalloc(sizeof(struct cifs_tcon), GFP_KERNEL); > if (!tcon) { > resched = true; > - list_del_init(&ses->rlist); > - cifs_put_smb_ses(ses); > + list_for_each_entry_safe(ses, ses2, &tmp_ses_list, rlist) { > + list_del_init(&ses->rlist); > + cifs_put_smb_ses(ses); > + } > goto done; > } > > > base-commit: 14702b3b2438e2f2d07ae93b5d695c166e5c83d1 > -- > 2.17.1 > Hi Xiaomeng, Good catch. Reviewed-by: Shyam Prasad N <sprasad@microsoft.com> Steve, This one needs to be marked for CC stable 5.17+
cc:stable too? On Tue, Mar 22, 2022 at 1:09 AM Shyam Prasad N via samba-technical <samba-technical@lists.samba.org> wrote: > > On Mon, Mar 21, 2022 at 3:50 PM Xiaomeng Tong <xiam0nd.tong@gmail.com> wrote: > > > > The bug is here: > > if (!tcon) { > > resched = true; > > list_del_init(&ses->rlist); > > cifs_put_smb_ses(ses); > > > > Because the list_for_each_entry() never exits early (without any > > break/goto/return inside the loop), the iterator 'ses' after the > > loop will always be an pointer to a invalid struct containing the > > HEAD (&pserver->smb_ses_list). As a result, the uses of 'ses' above > > will lead to a invalid memory access. > > > > The original intention should have been to walk each entry 'ses' in > > '&tmp_ses_list', delete '&ses->rlist' and put 'ses'. So fix it with > > a list_for_each_entry_safe(). > > > > Fixes: 3663c9045f51a ("cifs: check reconnects for channels of active tcons too") > > Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com> > > --- > > fs/cifs/smb2pdu.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c > > index 7e7909b1ae11..f82d6fcb5c64 100644 > > --- a/fs/cifs/smb2pdu.c > > +++ b/fs/cifs/smb2pdu.c > > @@ -3858,8 +3858,10 @@ void smb2_reconnect_server(struct work_struct *work) > > tcon = kzalloc(sizeof(struct cifs_tcon), GFP_KERNEL); > > if (!tcon) { > > resched = true; > > - list_del_init(&ses->rlist); > > - cifs_put_smb_ses(ses); > > + list_for_each_entry_safe(ses, ses2, &tmp_ses_list, rlist) { > > + list_del_init(&ses->rlist); > > + cifs_put_smb_ses(ses); > > + } > > goto done; > > } > > > > > > base-commit: 14702b3b2438e2f2d07ae93b5d695c166e5c83d1 > > -- > > 2.17.1 > > > > Hi Xiaomeng, > Good catch. > Reviewed-by: Shyam Prasad N <sprasad@microsoft.com> > > Steve, This one needs to be marked for CC stable 5.17+ > > -- > Regards, > Shyam >
tentatively merged into cifs-2.6.git for-next pending additional testing Also added cc:stable 5.17 On Tue, Mar 22, 2022 at 1:09 AM Shyam Prasad N via samba-technical <samba-technical@lists.samba.org> wrote: > > On Mon, Mar 21, 2022 at 3:50 PM Xiaomeng Tong <xiam0nd.tong@gmail.com> wrote: > > > > The bug is here: > > if (!tcon) { > > resched = true; > > list_del_init(&ses->rlist); > > cifs_put_smb_ses(ses); > > > > Because the list_for_each_entry() never exits early (without any > > break/goto/return inside the loop), the iterator 'ses' after the > > loop will always be an pointer to a invalid struct containing the > > HEAD (&pserver->smb_ses_list). As a result, the uses of 'ses' above > > will lead to a invalid memory access. > > > > The original intention should have been to walk each entry 'ses' in > > '&tmp_ses_list', delete '&ses->rlist' and put 'ses'. So fix it with > > a list_for_each_entry_safe(). > > > > Fixes: 3663c9045f51a ("cifs: check reconnects for channels of active tcons too") > > Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com> > > --- > > fs/cifs/smb2pdu.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c > > index 7e7909b1ae11..f82d6fcb5c64 100644 > > --- a/fs/cifs/smb2pdu.c > > +++ b/fs/cifs/smb2pdu.c > > @@ -3858,8 +3858,10 @@ void smb2_reconnect_server(struct work_struct *work) > > tcon = kzalloc(sizeof(struct cifs_tcon), GFP_KERNEL); > > if (!tcon) { > > resched = true; > > - list_del_init(&ses->rlist); > > - cifs_put_smb_ses(ses); > > + list_for_each_entry_safe(ses, ses2, &tmp_ses_list, rlist) { > > + list_del_init(&ses->rlist); > > + cifs_put_smb_ses(ses); > > + } > > goto done; > > } > > > > > > base-commit: 14702b3b2438e2f2d07ae93b5d695c166e5c83d1 > > -- > > 2.17.1 > > > > Hi Xiaomeng, > Good catch. > Reviewed-by: Shyam Prasad N <sprasad@microsoft.com> > > Steve, This one needs to be marked for CC stable 5.17+ > > -- > Regards, > Shyam >
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index 7e7909b1ae11..f82d6fcb5c64 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -3858,8 +3858,10 @@ void smb2_reconnect_server(struct work_struct *work) tcon = kzalloc(sizeof(struct cifs_tcon), GFP_KERNEL); if (!tcon) { resched = true; - list_del_init(&ses->rlist); - cifs_put_smb_ses(ses); + list_for_each_entry_safe(ses, ses2, &tmp_ses_list, rlist) { + list_del_init(&ses->rlist); + cifs_put_smb_ses(ses); + } goto done; }
The bug is here: if (!tcon) { resched = true; list_del_init(&ses->rlist); cifs_put_smb_ses(ses); Because the list_for_each_entry() never exits early (without any break/goto/return inside the loop), the iterator 'ses' after the loop will always be an pointer to a invalid struct containing the HEAD (&pserver->smb_ses_list). As a result, the uses of 'ses' above will lead to a invalid memory access. The original intention should have been to walk each entry 'ses' in '&tmp_ses_list', delete '&ses->rlist' and put 'ses'. So fix it with a list_for_each_entry_safe(). Fixes: 3663c9045f51a ("cifs: check reconnects for channels of active tcons too") Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com> --- fs/cifs/smb2pdu.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) base-commit: 14702b3b2438e2f2d07ae93b5d695c166e5c83d1