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[104.218.69.129]) by smtp.gmail.com with ESMTPSA id u6-20020a02c046000000b0046e33e82782sm2930639jam.135.2024.01.31.10.32.42 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 31 Jan 2024 10:32:43 -0800 (PST) From: Bethany Jamison To: kernel-team@lists.ubuntu.com Subject: [SRU][Mantic][Jammy][Focal][PATCH 1/1] ida: Fix crash in ida_free when the bitmap is empty Date: Wed, 31 Jan 2024 12:32:41 -0600 Message-Id: <20240131183241.12938-2-bethany.jamison@canonical.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240131183241.12938-1-bethany.jamison@canonical.com> References: <20240131183241.12938-1-bethany.jamison@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: "Matthew Wilcox (Oracle)" The IDA usually detects double-frees, but that detection failed to consider the case when there are no nearby IDs allocated and so we have a NULL bitmap rather than simply having a clear bit. Add some tests to the test-suite to be sure we don't inadvertently reintroduce this problem. Unfortunately they're quite noisy so include a message to disregard the warnings. Reported-by: Zhenghan Wang Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Linus Torvalds (cherry picked from commit af73483f4e8b6f5c68c9aa63257bdd929a9c194a) CVE-2023-6915 Signed-off-by: Bethany Jamison --- lib/idr.c | 2 +- lib/test_ida.c | 40 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+), 1 deletion(-) diff --git a/lib/idr.c b/lib/idr.c index 13f2758c23773..da36054c3ca02 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -508,7 +508,7 @@ void ida_free(struct ida *ida, unsigned int id) goto delete; xas_store(&xas, xa_mk_value(v)); } else { - if (!test_bit(bit, bitmap->bitmap)) + if (!bitmap || !test_bit(bit, bitmap->bitmap)) goto err; __clear_bit(bit, bitmap->bitmap); xas_set_mark(&xas, XA_FREE_MARK); diff --git a/lib/test_ida.c b/lib/test_ida.c index b068806259615..55105baa19da9 100644 --- a/lib/test_ida.c +++ b/lib/test_ida.c @@ -150,6 +150,45 @@ static void ida_check_conv(struct ida *ida) IDA_BUG_ON(ida, !ida_is_empty(ida)); } +/* + * Check various situations where we attempt to free an ID we don't own. + */ +static void ida_check_bad_free(struct ida *ida) +{ + unsigned long i; + + printk("vvv Ignore \"not allocated\" warnings\n"); + /* IDA is empty; all of these will fail */ + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + + /* IDA contains a single value entry */ + IDA_BUG_ON(ida, ida_alloc_min(ida, 3, GFP_KERNEL) != 3); + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + + /* IDA contains a single bitmap */ + IDA_BUG_ON(ida, ida_alloc_min(ida, 1023, GFP_KERNEL) != 1023); + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + + /* IDA contains a tree */ + IDA_BUG_ON(ida, ida_alloc_min(ida, (1 << 20) - 1, GFP_KERNEL) != (1 << 20) - 1); + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + printk("^^^ \"not allocated\" warnings over\n"); + + ida_free(ida, 3); + ida_free(ida, 1023); + ida_free(ida, (1 << 20) - 1); + + IDA_BUG_ON(ida, !ida_is_empty(ida)); +} + static DEFINE_IDA(ida); static int ida_checks(void) @@ -162,6 +201,7 @@ static int ida_checks(void) ida_check_leaf(&ida, 1024 * 64); ida_check_max(&ida); ida_check_conv(&ida); + ida_check_bad_free(&ida); printk("IDA: %u of %u tests passed\n", tests_passed, tests_run); return (tests_run != tests_passed) ? 0 : -EINVAL;