From 5a0e3ad6af8660be21ca98a971cd00f331318c05 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 24 Mar 2010 17:04:11 +0900 Subject: include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo Guess-its-ok-by: Christoph Lameter Cc: Ingo Molnar Cc: Lee Schermerhorn --- kernel/cred.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/cred.c') diff --git a/kernel/cred.c b/kernel/cred.c index 1ed8ca18790c..d84bdef17c9f 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -10,6 +10,7 @@ */ #include #include +#include #include #include #include -- cgit v1.2.1 From eff30363c0b8b057f773108589bfd8881659fe74 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 20 Apr 2010 22:41:18 +0100 Subject: CRED: Fix double free in prepare_usermodehelper_creds() error handling Patch 570b8fb505896e007fd3bb07573ba6640e51851d: Author: Mathieu Desnoyers Date: Tue Mar 30 00:04:00 2010 +0100 Subject: CRED: Fix memory leak in error handling attempts to fix a memory leak in the error handling by making the offending return statement into a jump down to the bottom of the function where a kfree(tgcred) is inserted. This is, however, incorrect, as it does a kfree() after doing put_cred() if security_prepare_creds() fails. That will result in a double free if 'error' is jumped to as put_cred() will also attempt to free the new tgcred record by virtue of it being pointed to by the new cred record. Signed-off-by: David Howells Signed-off-by: James Morris --- kernel/cred.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel/cred.c') diff --git a/kernel/cred.c b/kernel/cred.c index e1dbe9eef800..ce1a52b9e8a3 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -398,6 +398,8 @@ struct cred *prepare_usermodehelper_creds(void) error: put_cred(new); + return NULL; + free_tgcred: #ifdef CONFIG_KEYS kfree(tgcred); -- cgit v1.2.1 From e134d200d57d43b171dcb0b55c178a1a0c7db14a Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 21 Apr 2010 10:28:25 +0100 Subject: CRED: Fix a race in creds_are_invalid() in credentials debugging creds_are_invalid() reads both cred->usage and cred->subscribers and then compares them to make sure the number of processes subscribed to a cred struct never exceeds the refcount of that cred struct. The problem is that this can cause a race with both copy_creds() and exit_creds() as the two counters, whilst they are of atomic_t type, are only atomic with respect to themselves, and not atomic with respect to each other. This means that if creds_are_invalid() can read the values on one CPU whilst they're being modified on another CPU, and so can observe an evolving state in which the subscribers count now is greater than the usage count a moment before. Switching the order in which the counts are read cannot help, so the thing to do is to remove that particular check. I had considered rechecking the values to see if they're in flux if the test fails, but I can't guarantee they won't appear the same, even if they've changed several times in the meantime. Note that this can only happen if CONFIG_DEBUG_CREDENTIALS is enabled. The problem is only likely to occur with multithreaded programs, and can be tested by the tst-eintr1 program from glibc's "make check". The symptoms look like: CRED: Invalid credentials CRED: At include/linux/cred.h:240 CRED: Specified credentials: ffff88003dda5878 [real][eff] CRED: ->magic=43736564, put_addr=(null) CRED: ->usage=766, subscr=766 CRED: ->*uid = { 0,0,0,0 } CRED: ->*gid = { 0,0,0,0 } CRED: ->security is ffff88003d72f538 CRED: ->security {359, 359} ------------[ cut here ]------------ kernel BUG at kernel/cred.c:850! ... RIP: 0010:[] [] __invalid_creds+0x4e/0x52 ... Call Trace: [] copy_creds+0x6b/0x23f Note the ->usage=766 and subscr=766. The values appear the same because they've been re-read since the check was made. Reported-by: Roland McGrath Signed-off-by: David Howells Signed-off-by: James Morris --- kernel/cred.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'kernel/cred.c') diff --git a/kernel/cred.c b/kernel/cred.c index ce1a52b9e8a3..62af1816c235 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -793,8 +793,6 @@ bool creds_are_invalid(const struct cred *cred) { if (cred->magic != CRED_MAGIC) return true; - if (atomic_read(&cred->usage) < atomic_read(&cred->subscribers)) - return true; #ifdef CONFIG_SECURITY_SELINUX if (selinux_is_enabled()) { if ((unsigned long) cred->security < PAGE_SIZE) -- cgit v1.2.1