Messages in this thread | | | Date | Tue, 13 Sep 2022 07:26:56 +0200 | Subject | Re: [PATCH] mm/slub: fix to return errno if kmalloc() fails | From | Marion & Christophe JAILLET <> |
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Le 13/09/2022 à 05:42, Chao Yu a écrit : > On 2022/9/10 0:47, Christophe JAILLET wrote: >> Le 30/08/2022 à 16:10, Chao Yu a écrit : >>> From: Chao Yu <chao.yu@oppo.com> >>> >>> In create_unique_id(), kmalloc(, GFP_KERNEL) can fail due to >>> out-of-memory, if it fails, return errno correctly rather than >>> triggering panic via BUG_ON(); >>> >>> kernel BUG at mm/slub.c:5893! >>> Internal error: Oops - BUG: 0 [#1] PREEMPT SMP >>> >>> Call trace: [...] >>> >>> Cc: <stable@kernel.org> >>> Reported-by: syzbot+81684812ea68216e08c5@syzkaller.appspotmail.com >>> Signed-off-by: Chao Yu <chao.yu@oppo.com> >>> --- >>> mm/slub.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/mm/slub.c b/mm/slub.c >>> index 862dbd9af4f5..e6f3727b9ad2 100644 >>> --- a/mm/slub.c >>> +++ b/mm/slub.c >>> @@ -5890,7 +5890,8 @@ static char *create_unique_id(struct >>> kmem_cache *s) >>> char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL); >> >> Hi, >> >> looks that ID_STR_LENGTH could even be reduced to 32 or 16. >> >> The 2nd BUG_ON at the end of the function could certainly be just >> removed as well or remplaced by a: >> if (p > name + ID_STR_LENGTH - 1) { >> kfree(name); >> return -E<something>; >> } > > Hi Christophe, Vlastimil, > > Should I include this in v3? or may be in another patch?
Hi,
My own preference would be for 3 patches.
Yours, as-is. It fixes a specific issue spotted by syzbot.
Another one for removing a BUG_ON() (that, IIUC can't happen!) Mostly a clean-up or a good practice in order to remove BUG_ON() from the kernel we it can be handled another way.
Eventually a 3rd one for reducing ID_STR_LENGTH. I guess that it is safe to reduce it to 32 or 16, but the impact on RL would be so small, that I wonder if it worth proposing it.
Just my 2c,
CJ
> > Thanks, > >> >> Just my 2c, >> >> CJ >> >>> char *p = name; >>> - BUG_ON(!name); >>> + if (!name) >>> + return ERR_PTR(-ENOMEM); >>> *p++ = ':'; >>> /* >>> @@ -5948,6 +5949,8 @@ static int sysfs_slab_add(struct kmem_cache *s) >>> * for the symlinks. >>> */ >>> name = create_unique_id(s); >>> + if (IS_ERR(name)) >>> + return PTR_ERR(name); >>> } >>> s->kobj.kset = kset; >>
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