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    Subject[PATCH AUTOSEL 4.19 04/27] afs: Fix loop index mixup in afs_deliver_vl_get_entry_by_name_u()
    Date
    From: Marc Dionne <marc.dionne@auristor.com>

    [ Upstream commit 4a46fdba449a5cd890271df5a9e23927d519ed00 ]

    afs_deliver_vl_get_entry_by_name_u() scans through the vl entry
    received from the volume location server and builds a return list
    containing the sites that are currently valid. When assigning
    values for the return list, the index into the vl entry (i) is used
    rather than the one for the new list (entry->nr_server). If all
    sites are usable, this works out fine as the indices will match.
    If some sites are not valid, for example if AFS_VLSF_DONTUSE is
    set, fs_mask and the uuid will be set for the wrong return site.

    Fix this by using entry->nr_server as the index into the arrays
    being filled in rather than i.

    This can lead to EDESTADDRREQ errors if none of the returned sites
    have a valid fs_mask.

    Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation")
    Signed-off-by: Marc Dionne <marc.dionne@auristor.com>
    Signed-off-by: David Howells <dhowells@redhat.com>
    Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/afs/vlclient.c | 11 ++++++-----
    1 file changed, 6 insertions(+), 5 deletions(-)

    diff --git a/fs/afs/vlclient.c b/fs/afs/vlclient.c
    index c3b740813fc71..c7dd47eaff29d 100644
    --- a/fs/afs/vlclient.c
    +++ b/fs/afs/vlclient.c
    @@ -60,23 +60,24 @@ static int afs_deliver_vl_get_entry_by_name_u(struct afs_call *call)
    struct afs_uuid__xdr *xdr;
    struct afs_uuid *uuid;
    int j;
    + int n = entry->nr_servers;

    tmp = ntohl(uvldb->serverFlags[i]);
    if (tmp & AFS_VLSF_DONTUSE ||
    (new_only && !(tmp & AFS_VLSF_NEWREPSITE)))
    continue;
    if (tmp & AFS_VLSF_RWVOL) {
    - entry->fs_mask[i] |= AFS_VOL_VTM_RW;
    + entry->fs_mask[n] |= AFS_VOL_VTM_RW;
    if (vlflags & AFS_VLF_BACKEXISTS)
    - entry->fs_mask[i] |= AFS_VOL_VTM_BAK;
    + entry->fs_mask[n] |= AFS_VOL_VTM_BAK;
    }
    if (tmp & AFS_VLSF_ROVOL)
    - entry->fs_mask[i] |= AFS_VOL_VTM_RO;
    - if (!entry->fs_mask[i])
    + entry->fs_mask[n] |= AFS_VOL_VTM_RO;
    + if (!entry->fs_mask[n])
    continue;

    xdr = &uvldb->serverNumber[i];
    - uuid = (struct afs_uuid *)&entry->fs_server[i];
    + uuid = (struct afs_uuid *)&entry->fs_server[n];
    uuid->time_low = xdr->time_low;
    uuid->time_mid = htons(ntohl(xdr->time_mid));
    uuid->time_hi_and_version = htons(ntohl(xdr->time_hi_and_version));
    --
    2.20.1
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