| Message ID | 20240308150615.339103-1-pc@manguebit.com |
|---|---|
| State | New |
| Headers | show |
| Series | cifs.upcall: fix UAF in get_cachename_from_process_env() | expand |
Merged this and the other patch to the next branch. Thanks! -- Best regards, Pavel Shilovsky пт, 8 мар. 2024 г. в 07:06, Paulo Alcantara <pc@manguebit.com>: > > Whether lseek(2) fails or @bufsize * 2 > ENV_BUF_MAX, then @buf would > end up being freed twice. For instance: > > cifs-utils-7.0/cifs.upcall.c:501: freed_arg: "free" frees "buf". > cifs-utils-7.0/cifs.upcall.c:524: double_free: Calling "free" frees > pointer "buf" which has already been freed. > 522| } > 523| out_close: > 524|-> free(buf); > 525| close(fd); > 526| return cachename; > > Fix this by setting @buf to NULL after freeing it to prevent UAF. > > Fixes: ed97e4ecab4e ("cifs.upcall: allow scraping of KRB5CCNAME out of initiating task's /proc/<pid>/environ file") > Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> > --- > cifs.upcall.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/cifs.upcall.c b/cifs.upcall.c > index 52c03280dbe0..ff6f2bd271bc 100644 > --- a/cifs.upcall.c > +++ b/cifs.upcall.c > @@ -498,10 +498,11 @@ retry: > /* We read to the end of the buffer. Double and try again */ > syslog(LOG_DEBUG, "%s: read to end of buffer (%zu bytes)\n", > __func__, bufsize); > - free(buf); > - bufsize *= 2; > if (lseek(fd, 0, SEEK_SET) < 0) > goto out_close; > + free(buf); > + buf = NULL; > + bufsize *= 2; > goto retry; > } > > -- > 2.44.0 >
diff --git a/cifs.upcall.c b/cifs.upcall.c index 52c03280dbe0..ff6f2bd271bc 100644 --- a/cifs.upcall.c +++ b/cifs.upcall.c @@ -498,10 +498,11 @@ retry: /* We read to the end of the buffer. Double and try again */ syslog(LOG_DEBUG, "%s: read to end of buffer (%zu bytes)\n", __func__, bufsize); - free(buf); - bufsize *= 2; if (lseek(fd, 0, SEEK_SET) < 0) goto out_close; + free(buf); + buf = NULL; + bufsize *= 2; goto retry; }
Whether lseek(2) fails or @bufsize * 2 > ENV_BUF_MAX, then @buf would end up being freed twice. For instance: cifs-utils-7.0/cifs.upcall.c:501: freed_arg: "free" frees "buf". cifs-utils-7.0/cifs.upcall.c:524: double_free: Calling "free" frees pointer "buf" which has already been freed. 522| } 523| out_close: 524|-> free(buf); 525| close(fd); 526| return cachename; Fix this by setting @buf to NULL after freeing it to prevent UAF. Fixes: ed97e4ecab4e ("cifs.upcall: allow scraping of KRB5CCNAME out of initiating task's /proc/<pid>/environ file") Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> --- cifs.upcall.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)