On Wed, May 31, 2023 at 08:01:37AM +0300, Dmitry Antipov wrote:
On 5/30/23 23:21, Lucas De Marchi wrote:
I'd avoid the unbalanced brackets and replace the bucket->entries
check with a return-early style. Would you be ok with me squashing this
into your patch?
Sure as you wish.
However I'm curious about this *runtime* error you went through. Does it
have a backtrace? There are other places we call bsearch() passing
bucket->entries, but that should be an imposibble runtime situation
since we bail out on context creation if we can't create the hash table.
This one is from something running under 'make check' (note I've added sleep()
calls to have a time frame to attach gdb, so actual line numbers are shifted):
(gdb) bt
#0 0x000000000040924a in hash_find (hash=0x1034400, key=0x7fff71657d50 "btusb") at shared/hash.c:246
#1 0x0000000000405661 in kmod_pool_get_module (ctx=0x10342a0, key=0x7fff71657d50 "btusb")
at libkmod/libkmod.c:403
#2 0x0000000000407cfe in kmod_module_new (ctx=0x10342a0, key=0x7fff71657d50 "btusb",
name=0x7fff71657d50 "btusb", namelen=5, alias=0x0, aliaslen=0, mod=0x7fff71658d88)
at libkmod/libkmod-module.c:270
#3 0x0000000000407f3f in kmod_module_new_from_name (ctx=0x10342a0, name=0x7fff71658d90 "btusb",
mod=0x7fff71658d88) at libkmod/libkmod-module.c:341
#4 0x000000000040824b in kmod_module_new_from_loaded (ctx=0x10342a0, list=0x7fff71659df8)
at libkmod/libkmod-module.c:1736
#5 0x000000000040262a in loaded_1 (t=0x40c0b8 <sloaded_10>) at testsuite/test-loaded.c:41
#6 0x0000000000402be9 in test_run_spawned (t=0x40c0b8 <sloaded_10>) at testsuite/testsuite.c:151
#7 0x0000000000404d3e in test_run (t=0x40c0b8 <sloaded_10>) at testsuite/testsuite.c:1080
#8 0x00000000004028ac in main (argc=3, argv=0x7fff7165a038) at testsuite/test-loaded.c:91
ok, that makes sense. I had missed that code path.
applied, thanks
Lucas De Marchi
(gdb) bt full
#0 0x000000000040924a in hash_find (hash=0x1034400, key=0x7fff71657d50 "btusb") at shared/hash.c:246
keylen = 5
hashval = 2921571348
pos = 20
bucket = 0x1034558
se = {key = 0x7fff71657d50 "btusb", value = 0x0}
entry = 0x0
(More stack frames follow...)
(gdb) p *((struct hash_bucket *)0x1034558)
$1 = {entries = 0x0, used = 0, total = 0}
That is, the bucket is non-NULL but empty, so bsearch() is called
as bsearch([whatever], NULL, 0, [some more stuff]). On my system
(Fedora 38 with glibc 2.37), bsearch() is declared as:
extern void *bsearch (const void *__key, const void *__base,
size_t __nmemb, size_t __size, __compar_fn_t __compar)
__nonnull ((1, 2, 5));
So NULL '__base' causes the sanitizer to complain.
Dmitry
