Messages in this thread Patch in this message | | | Date | Tue, 23 Aug 2022 23:03:58 +0300 | Subject | Re: bpf selftest failed in 5.4.210 kernel | From | Ovidiu Panait <> |
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Hi Jean-Philippe,
On 8/23/22 21:34, Jean-Philippe Brucker wrote: > [Please note: This e-mail is from an EXTERNAL e-mail address] > > On Tue, Aug 23, 2022 at 10:31:40AM +0300, RAJESH DASARI wrote: >> Sorry for the confusion, results are indeed confusing to me . >> If I try with git bisect I get >> >> git bisect bad >> 9d6f67365d9cdb389fbdac2bb5b00e59e345930e is the first bad commit > For me bisecting points to: > > (A) 7c1134c7da99 ("bpf: Verifer, adjust_scalar_min_max_vals to always call update_reg_bounds()") > > This changes the BPF verifier output and (as expected) breaks the > test_align selftest. That's why in the same series [1] another patch fixed > test_align. In v5.4.y, that patch is: > > (B) 6a9b3f0f3bad ("selftests/bpf: Fix test_align verifier log patterns") > > Unfortunately commit (B) addresses multiple verifier changes, not solely > (A). My guess is those changes were in series [1] and haven't been > backported to v5.4. So multiple solutions: > > * Partially revert (B), only keeping the changes needed by (A) > * Revert (A) and (B) > * Add the missing commits that (B) also addresses > > I don't know which, I suppose it depends on the intent behind backporting > (A). Ovidiu?
The intent behind backporting 7c1134c7da99 ("bpf: Verifer, adjust_scalar_min_max_vals to always call update_reg_bounds()") was to fix CVE-2021-4159.
If we revert test 11 changes brought in by 6a9b3f0f3bad ("selftests/bpf: Fix test_align verifier log patterns") backport, all test_align testcases pass on my side:
diff --git a/tools/testing/selftests/bpf/test_align.c b/tools/testing/selftests/bpf/test_align.c index c9c9bdce9d6d..4726e3eca9b2 100644 --- a/tools/testing/selftests/bpf/test_align.c +++ b/tools/testing/selftests/bpf/test_align.c @@ -580,18 +580,18 @@ static struct bpf_align_test tests[] = { /* Adding 14 makes R6 be (4n+2) */ {11, "R6_w=inv(id=0,umin_value=14,umax_value=74,var_off=(0x2; 0x7c))"}, /* Subtracting from packet pointer overflows ubounds */ - {13, "R5_w=pkt(id=1,off=0,r=8,umin_value=18446744073709551542,umax_value=18446744073709551602,var_off=(0xffffffffffffff82; 0x7c)"}, + {13, "R5_w=pkt(id=1,off=0,r=8,umin_value=18446744073709551542,umax_value=18446744073709551602,var_off=(0xffffffffffffff82; 0x7c))"}, /* New unknown value in R7 is (4n), >= 76 */ {15, "R7_w=inv(id=0,umin_value=76,umax_value=1096,var_off=(0x0; 0x7fc))"}, /* Adding it to packet pointer gives nice bounds again */ - {16, "R5_w=pkt(id=2,off=0,r=0,umin_value=2,umax_value=1082,var_off=(0x2; 0xfffffffc)"}, + {16, "R5_w=pkt(id=2,off=0,r=0,umin_value=2,umax_value=1082,var_off=(0x2; 0x7fc))"}, /* At the time the word size load is performed from R5, * its total fixed offset is NET_IP_ALIGN + reg->off (0) * which is 2. Then the variable offset is (4n+2), so * the total offset is 4-byte aligned and meets the * load's requirements. */ - {20, "R5=pkt(id=2,off=0,r=4,umin_value=2,umax_value=1082,var_off=(0x2; 0xfffffffc)"}, + {20, "R5=pkt(id=2,off=0,r=4,umin_value=2,umax_value=1082,var_off=(0x2; 0x7fc))"}, }, }, }; root@intel-x86-64:~/bpf# ./test_align Test 0: mov ... PASS Test 1: shift ... PASS Test 2: addsub ... PASS Test 3: mul ... PASS Test 4: unknown shift ... PASS Test 5: unknown mul ... PASS Test 6: packet const offset ... PASS Test 7: packet variable offset ... PASS Test 8: packet variable offset 2 ... PASS Test 9: dubious pointer arithmetic ... PASS Test 10: variable subtraction ... PASS Test 11: pointer variable subtraction ... PASS Results: 12 pass 0 fail
> In any case 6098562ed9df ("selftests/bpf: Fix "dubious pointer arithmetic" > test") can be reverted, I can send that once we figure out the rest.
In my testing, with [1] and [2] applied, but without [3], the following test_align selftest would still fail:
Test 9: dubious pointer arithmetic ... Failed to find match 9: R5=inv(id=0,umin_value=2,umax_value=9223372034707292158,var_off=(0x2; 0x7fffffff7ffffffc)
[1] 7c1134c7da99 ("bpf: Verifer, adjust_scalar_min_max_vals to always call update_reg_bounds()")
[2] 6a9b3f0f3bad ("selftests/bpf: Fix test_align verifier log patterns")
[3] 6098562ed9df ("selftests/bpf: Fix "dubious pointer arithmetic" test")
> Thanks, > Jean > > [1] https://lore.kernel.org/bpf/158507130343.15666.8018068546764556975.stgit@john-Precision-5820-Tower/ > >> If I try to test myself with multiple test scenarios(I have mentioned >> in the previous mails) for the bad commits , I see that bad commits >> are >> bpf: Verifer, adjust_scalar_min_max_vals to always call update_reg_bounds() >> selftests/bpf: Fix test_align verifier log patterns >> selftests/bpf: Fix "dubious pointer arithmetic" test >> >> Thanks, >> Rajesh Dasari. >> >> On Tue, Aug 23, 2022 at 10:04 AM Greg KH <gregkh@linuxfoundation.org> wrote: >>> On Mon, Aug 22, 2022 at 10:23:02PM +0300, RAJESH DASARI wrote: >>>> Hi, >>>> >>>> Please find the test scenarios which I have tried. >>>> >>>> Test 1: >>>> >>>> Running system Kernel version (tag/commit) : v5.4.210 >>>> Kernel source code checkout : v5.4.210 >>>> test_align test case execution status : Failure >>>> >>>> Test 2: >>>> >>>> Running system Kernel version (tag/commit) : v5.4.210 >>>> Kernel source code checkout : v5.4.209 >>>> test_align test case execution status : Failure >>>> >>>> Test 3: >>>> >>>> Running system Kernel version (tag/commit) : v5.4.209 >>>> Kernel source code checkout : v5.4.209 >>>> test_align test case execution status : Success >>>> >>>> Test 4: >>>> >>>> Running system Kernel version (tag/commit) : ACPI: APEI: Better fix to >>>> avoid spamming the console with old error logs ( Kernel compiled at >>>> this commit and system is booted with this change) >>>> Kernel source code checkout : v5.4.210 but reverted selftests/bpf: Fix >>>> test_align verifier log patterns and selftests/bpf: Fix "dubious >>>> pointer arithmetic" test. If I revert only the Fix "dubious pointer >>>> arithmetic" test, the testcase still fails. >>>> test_align test case execution status : Success >>>> >>>> Test 5: >>>> >>>> Running system Kernel version (tag/commit) : v5.4.210 but reverted >>>> commit (bpf: Verifer, adjust_scalar_min_max_vals to always call >>>> update_reg_bounds() ) >>>> Kernel source code checkout : v5.4.210 but reverted selftests/bpf: Fix >>>> test_align verifier log patterns and selftests/bpf: Fix "dubious >>>> pointer arithmetic" test. >>>> test_align test case execution status : Success >>>> >>>> Test 6 : >>>> >>>> Running system Kernel version (tag/commit) : bpf: Test_verifier, #70 >>>> error message updates for 32-bit right shift( Kernel compiled at this >>>> commit and system is booted with this change) >>>> Kernel source code checkout : v5.4.209 or v5.4.210 >>>> test_align test case execution status : Failure >>> I'm sorry, but I don't know what to do with this report at all. >>> >>> Is there some failure somewhere? If you use 'git bisect' do you find >>> the offending commit? >>> >>> confused, >>> >>> greg k-h
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