> On Sun, Dec 24, 2023 at 04:20:33PM +0800, Zhipeng Lu wrote:
> > The ctx->mech_used.data allocated by kmemdup is not freed in neither
> > gss_import_v2_context nor it only caller radeon_driver_open_kms.
> > Thus, this patch reform the last call of gss_import_v2_context to the
> > gss_krb5_import_ctx_v2, preventing the memleak while keepping the return
> > formation.
> >
> > Fixes: 47d848077629 ("gss_krb5: handle new context format from gssd")
> > Signed-off-by: Zhipeng Lu <alexious@xxxxxxxxxx>
> > ---
> > net/sunrpc/auth_gss/gss_krb5_mech.c | 9 ++++++++-
> > 1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/sunrpc/auth_gss/gss_krb5_mech.c b/net/sunrpc/auth_gss/gss_krb5_mech.c
> > index e31cfdf7eadc..1e54bd63e3f0 100644
> > --- a/net/sunrpc/auth_gss/gss_krb5_mech.c
> > +++ b/net/sunrpc/auth_gss/gss_krb5_mech.c
> > @@ -398,6 +398,7 @@ gss_import_v2_context(const void *p, const void *end, struct krb5_ctx *ctx,
> > u64 seq_send64;
> > int keylen;
> > u32 time32;
> > + int ret;
> >
> > p = simple_get_bytes(p, end, &ctx->flags, sizeof(ctx->flags));
> > if (IS_ERR(p))
> > @@ -450,8 +451,14 @@ gss_import_v2_context(const void *p, const void *end, struct krb5_ctx *ctx,
> > }
> > ctx->mech_used.len = gss_kerberos_mech.gm_oid.len;
> >
> > - return gss_krb5_import_ctx_v2(ctx, gfp_mask);
> > + ret = gss_krb5_import_ctx_v2(ctx, gfp_mask);
> > + if (ret) {
> > + p = ERR_PTR(ret);
> > + goto out_free;
> > + };
> >
> > +out_free:
> > + kfree(ctx->mech_used.data);
>
> If the caller's error flow does not invoke
> gss_krb5_delete_sec_context(), then I would expect more than just
> mech_used.data would be leaked. What if, instead, you changed
> gss_krb5_import_sec_context() like this (untested):
>
> 471 ret = gss_import_v2_context(p, end, ctx, gfp_mask);
> 472 memzero_explicit(&ctx->Ksess, sizeof(ctx->Ksess));
> 473 if (ret) {
> - kfree(ctx);
> + gss_krb5_delete_sec_context(ctx);
> 475 return ret;
> 476 }
>
> Obviously you would need to add a forward declaration of
> gss_krb5_import_sec_context() to make this compile. The question
> is whether gss_krb5_delete_sec_context() will deal with a partially-
> initialized @ctx.
Since the ctx is allocated just in gss_krb5_import_sec_context,
together with that all of gss_krb5_import_sec_context, gss_import_v2_context(with this patch)
and gss_krb5_import_ctx_v2 are allocation-free balanced. It seems that we don't need to
release anything else by invoking gss_krb5_delete_sec_context.
If I miss something leaked, please let me know.
>
> How did you find this leak, and what kind of testing was done to
> confirm the fix is safe?
I found this memleak by static analysis.
The safety issue can't be solved by automatic tools as far as I know.
So I check patches manuelly before sending patches.
> > out_err:
> > return PTR_ERR(p);
> > }
> > --
> > 2.34.1
> >
>
> --
> Chuck Lever
