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author | Eric Biggers <ebiggers@google.com> | 2020-07-08 23:15:20 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-08-11 16:48:09 +0300 |
commit | 5ec142a2e9e6542372f80c42184c8dfb97c69f14 (patch) | |
tree | a97cbdb1d8d4b015e88ecc51fda49f8b81f05a34 /scripts/nsdeps | |
parent | 382c0fa38c0e1341e4704fb65c0435630c6f8421 (diff) | |
download | linux-5ec142a2e9e6542372f80c42184c8dfb97c69f14.tar.xz |
Smack: fix use-after-free in smk_write_relabel_self()
commit beb4ee6770a89646659e6a2178538d2b13e2654e upstream.
smk_write_relabel_self() frees memory from the task's credentials with
no locking, which can easily cause a use-after-free because multiple
tasks can share the same credentials structure.
Fix this by using prepare_creds() and commit_creds() to correctly modify
the task's credentials.
Reproducer for "BUG: KASAN: use-after-free in smk_write_relabel_self":
#include <fcntl.h>
#include <pthread.h>
#include <unistd.h>
static void *thrproc(void *arg)
{
int fd = open("/sys/fs/smackfs/relabel-self", O_WRONLY);
for (;;) write(fd, "foo", 3);
}
int main()
{
pthread_t t;
pthread_create(&t, NULL, thrproc, NULL);
thrproc(NULL);
}
Reported-by: syzbot+e6416dabb497a650da40@syzkaller.appspotmail.com
Fixes: 38416e53936e ("Smack: limited capability for changing process label")
Cc: <stable@vger.kernel.org> # v4.4+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'scripts/nsdeps')
0 files changed, 0 insertions, 0 deletions