From 0250edf1eb4ff0b164c0cdabcbf4313507f3082e Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Tue, 3 Nov 2020 11:52:57 +0000 Subject: [PATCH] tests/qtest/libqos/ahci.c: Avoid NULL dereference in ahci_exec() In ahci_exec() we attempt to permit the caller to pass a NULL pointer for opts_in (in which case we use a default set of options). However although we check for NULL when setting up the opts variable at the top of the function, we unconditionally dereference opts_in at the end of the function as part of freeing the opts->buffer. Switch to checking whether the final buffer is the same as the buffer we started with, instead of assuming the value we started with is always opts_in->buffer. At the moment all the callers pass a non-NULL opts argument, so we never saw any crashes in practice. Fixes: Coverity CID 1432302 Signed-off-by: Peter Maydell Message-Id: <20201103115257.23623-1-peter.maydell@linaro.org> Signed-off-by: Paolo Bonzini --- tests/qtest/libqos/ahci.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/tests/qtest/libqos/ahci.c b/tests/qtest/libqos/ahci.c index 2946abc15a..fba3e7a954 100644 --- a/tests/qtest/libqos/ahci.c +++ b/tests/qtest/libqos/ahci.c @@ -637,10 +637,13 @@ void ahci_exec(AHCIQState *ahci, uint8_t port, AHCICommand *cmd; int rc; AHCIOpts *opts; + uint64_t buffer_in; opts = g_memdup((opts_in == NULL ? &default_opts : opts_in), sizeof(AHCIOpts)); + buffer_in = opts->buffer; + /* No guest buffer provided, create one. */ if (opts->size && !opts->buffer) { opts->buffer = ahci_alloc(ahci, opts->size); @@ -686,7 +689,7 @@ void ahci_exec(AHCIQState *ahci, uint8_t port, g_assert_cmpint(rc, ==, 0); } ahci_command_free(cmd); - if (opts->buffer != opts_in->buffer) { + if (opts->buffer != buffer_in) { ahci_free(ahci, opts->buffer); } g_free(opts); -- 2.30.2