On Tue, 2025-01-14 at 23:45 +0100, Antoine Viallon wrote: > We now free the temporary target path substring allocation on every > possible branch, instead of omitting the default branch. > In some cases, a memory leak occured, which could rapidly crash the > system (depending on how many file accesses were attempted). > > This was detected in production because it caused a continuous memory > growth, > eventually triggering kernel OOM and completely hard-locking the > kernel. > > Relevant kmemleak stacktrace: > > unreferenced object 0xffff888131e69900 (size 128): > comm "git", pid 66104, jiffies 4295435999 > hex dump (first 32 bytes): > 76 6f 6c 75 6d 65 73 2f 63 6f 6e 74 61 69 6e 65 > volumes/containe > 72 73 2f 67 69 74 65 61 2f 67 69 74 65 61 2f 67 > rs/gitea/gitea/g > backtrace (crc 2f3bb450): > [<ffffffffaa68fb49>] __kmalloc_noprof+0x359/0x510 > [<ffffffffc32bf1df>] ceph_mds_check_access+0x5bf/0x14e0 > [ceph] > [<ffffffffc3235722>] ceph_open+0x312/0xd80 [ceph] > [<ffffffffaa7dd786>] do_dentry_open+0x456/0x1120 > [<ffffffffaa7e3729>] vfs_open+0x79/0x360 > [<ffffffffaa832875>] path_openat+0x1de5/0x4390 > [<ffffffffaa834fcc>] do_filp_open+0x19c/0x3c0 > [<ffffffffaa7e44a1>] do_sys_openat2+0x141/0x180 > [<ffffffffaa7e4945>] __x64_sys_open+0xe5/0x1a0 > [<ffffffffac2cc2f7>] do_syscall_64+0xb7/0x210 > [<ffffffffac400130>] entry_SYSCALL_64_after_hwframe+0x77/0x7f > > It can be triggered by mouting a subdirectory of a CephFS filesystem, > and then trying to access files on this subdirectory with an auth > token using a path-scoped capability: > > $ ceph auth get client.services > [client.services] > key = REDACTED > caps mds = "allow rw fsname=cephfs path=/volumes/" > caps mon = "allow r fsname=cephfs" > caps osd = "allow rw tag cephfs data=cephfs" > > $ cat /proc/self/mounts > > services@00000000-0000-0000-0000-000000000000.cephfs=/volumes/contain > ers /ceph/containers ceph > rw,noatime,name=services,secret=<hidden>,ms_mode=prefer- > crc,mount_timeout=300,acl,mon_addr=[REDACTED]:3300,recover_session=cl > ean 0 0 > > $ seq 1 1000000 | xargs -P32 --replace={} touch > /ceph/containers/file-{} && \ > seq 1 1000000 | xargs -P32 --replace={} cat > /ceph/containers/file-{} > > Signed-off-by: Antoine Viallon <antoine@xxxxxxxxxxxxx> > --- > fs/ceph/mds_client.c | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c > index 785fe489ef4b..c3b63243c2dd 100644 > --- a/fs/ceph/mds_client.c > +++ b/fs/ceph/mds_client.c > @@ -5690,18 +5690,21 @@ static int ceph_mds_auth_match(struct > ceph_mds_client *mdsc, > * > * All the other cases > --> mismatch > */ > + int rc = 1; > char *first = strstr(_tpath, auth- > >match.path); > if (first != _tpath) { > - if (free_tpath) > - kfree(_tpath); > - return 0; > + rc = 0; > } > > if (tlen > len && _tpath[len] != '/') { > - if (free_tpath) > - kfree(_tpath); > - return 0; > + rc = 0; > } > + > + if (free_tpath) > + kfree(_tpath); > + > + if (!rc) > + return 0; > } > } > Looks good. Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@xxxxxxx> Thanks, Slava.