* [PATCH] staging: vt6655: fix potential memory leak @ 2022-09-09 14:13 Nam Cao 2022-09-09 14:42 ` Nam Cao ` (2 more replies) 0 siblings, 3 replies; 6+ messages in thread From: Nam Cao @ 2022-09-09 14:13 UTC (permalink / raw) To: forest, gregkh; +Cc: namcaov, linux-kernel, linux-staging In function device_init_td0_ring, memory is allocated for member td_info of priv->apTD0Rings[i], with i increasing from 0. In case of allocation failure, the memory is freed in reversed order, with i decreasing to 0. However, the case i=0 is left out and thus memory is leaked. Modify the memory freeing loop to include the case i=0. Signed-off-by: Nam Cao <namcaov@gmail.com> --- drivers/staging/vt6655/device_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/staging/vt6655/device_main.c b/drivers/staging/vt6655/device_main.c index 3397c78b975a..a65014195fdc 100644 --- a/drivers/staging/vt6655/device_main.c +++ b/drivers/staging/vt6655/device_main.c @@ -743,7 +743,7 @@ static int device_init_td0_ring(struct vnt_private *priv) return 0; err_free_desc: - while (--i) { + while (i--) { desc = &priv->apTD0Rings[i]; kfree(desc->td_info); } -- 2.25.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] staging: vt6655: fix potential memory leak 2022-09-09 14:13 [PATCH] staging: vt6655: fix potential memory leak Nam Cao @ 2022-09-09 14:42 ` Nam Cao 2022-09-12 14:17 ` Dan Carpenter 2022-09-09 17:59 ` Philipp Hortmann 2022-09-12 13:25 ` Dan Carpenter 2 siblings, 1 reply; 6+ messages in thread From: Nam Cao @ 2022-09-09 14:42 UTC (permalink / raw) To: forest, gregkh; +Cc: linux-kernel, linux-staging I did not realize this initially, but this bug can cause more serious problem than just a memory leak. In the case that kzalloc fails right from the beginning with i=0; then in the while loop, "i" will wrap around and the code will access priv->apTD0Rings[4294967295] which is obviously not good. Best regards, Nam ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] staging: vt6655: fix potential memory leak 2022-09-09 14:42 ` Nam Cao @ 2022-09-12 14:17 ` Dan Carpenter 2022-09-12 14:53 ` Dan Carpenter 0 siblings, 1 reply; 6+ messages in thread From: Dan Carpenter @ 2022-09-12 14:17 UTC (permalink / raw) To: Nam Cao; +Cc: forest, gregkh, linux-kernel, linux-staging On Fri, Sep 09, 2022 at 04:42:05PM +0200, Nam Cao wrote: > I did not realize this initially, but this bug can cause more serious problem > than just a memory leak. In the case that kzalloc fails right from the > beginning with i=0; then in the while loop, "i" will wrap around and the code > will access priv->apTD0Rings[4294967295] which is obviously not good. > True. You probably want to resend with that added to the commit message. I will create a Smatch check to prevent these in the future. regards, dan carpenter ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] staging: vt6655: fix potential memory leak 2022-09-12 14:17 ` Dan Carpenter @ 2022-09-12 14:53 ` Dan Carpenter 0 siblings, 0 replies; 6+ messages in thread From: Dan Carpenter @ 2022-09-12 14:53 UTC (permalink / raw) To: Nam Cao; +Cc: forest, gregkh, linux-kernel, linux-staging [-- Attachment #1: Type: text/plain, Size: 1814 bytes --] On Mon, Sep 12, 2022 at 05:17:28PM +0300, Dan Carpenter wrote: > On Fri, Sep 09, 2022 at 04:42:05PM +0200, Nam Cao wrote: > > I did not realize this initially, but this bug can cause more serious problem > > than just a memory leak. In the case that kzalloc fails right from the > > beginning with i=0; then in the while loop, "i" will wrap around and the code > > will access priv->apTD0Rings[4294967295] which is obviously not good. > > > > True. You probably want to resend with that added to the commit > message. I will create a Smatch check to prevent these in the future. > I created a static checker warning for these and it found a bunch more bugs in the same file. drivers/staging/vt6655/device_main.c:635 device_init_rd0_ring() warn: potential decrement underflow 'i' rl='s32min-(-1)' (iterator) drivers/staging/vt6655/device_main.c:636 device_init_rd0_ring() warn: using underflowed offset 'i' drivers/staging/vt6655/device_main.c:681 device_init_rd1_ring() warn: potential decrement underflow 'i' rl='s32min-(-1)' (iterator) drivers/staging/vt6655/device_main.c:682 device_init_rd1_ring() warn: using underflowed offset 'i' drivers/staging/vt6655/device_main.c:746 device_init_td0_ring() warn: potential decrement underflow 'i' rl='s32min-(-1)' (iterator) drivers/staging/vt6655/device_main.c:747 device_init_td0_ring() warn: using underflowed offset 'i' drivers/staging/vt6655/device_main.c:786 device_init_td1_ring() warn: potential decrement underflow 'i' rl='s32min-(-1)' (iterator) drivers/staging/vt6655/device_main.c:787 device_init_td1_ring() warn: using underflowed offset 'i' Could you fix those as well? They're all the same bug and the same file so I would do it all at once. They were introduced in the same patch as well so only one Fixes tag required. regards, dan carpenter [-- Attachment #2: check_decrement_underflow.c --] [-- Type: text/x-csrc, Size: 2137 bytes --] /* * Copyright (C) 2022 Oracle. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt */ #include "smatch.h" #include "smatch_extra.h" #include "smatch_slist.h" static int my_id; STATE(decremented); static struct expression *prev; static void match_condition(struct expression *expr) { struct expression *orig = expr; struct statement *stmt; struct range_list *rl; const char *iterator = ""; char *name; if (expr == prev) return; if (expr->type != EXPR_PREOP || expr->op != SPECIAL_DECREMENT) return; expr = strip_expr(expr->unop); get_absolute_rl(expr, &rl); if (rl_min(rl).value > 0) return; set_state_expr(my_id, expr, &decremented); stmt = get_parent_stmt(orig); if (stmt && stmt->type == STMT_ITERATOR) iterator = " (iterator)"; prev = orig; name = expr_to_str(expr); sm_warning("potential decrement underflow '%s' rl='%s'%s", name, show_rl(rl), iterator); free_string(name); } static void array_check(struct expression *expr) { struct expression *array, *offset; struct range_list *rl; char *name; expr = strip_expr(expr); array = get_array_base(expr); offset = get_array_offset(expr); if (!array || !offset) return; if (!get_state_expr(my_id, offset)) return; get_absolute_rl(offset, &rl); if (rl_min(rl).value >= 0) return; name = expr_to_str(offset); sm_warning("using underflowed offset '%s'", name); free_string(name); } void check_decrement_underflow(int id) { my_id = id; add_hook(&match_condition, CONDITION_HOOK); add_hook(&array_check, OP_HOOK); } ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] staging: vt6655: fix potential memory leak 2022-09-09 14:13 [PATCH] staging: vt6655: fix potential memory leak Nam Cao 2022-09-09 14:42 ` Nam Cao @ 2022-09-09 17:59 ` Philipp Hortmann 2022-09-12 13:25 ` Dan Carpenter 2 siblings, 0 replies; 6+ messages in thread From: Philipp Hortmann @ 2022-09-09 17:59 UTC (permalink / raw) To: Nam Cao, forest, gregkh; +Cc: linux-kernel, linux-staging On 9/9/22 16:13, Nam Cao wrote: > In function device_init_td0_ring, memory is allocated for member > td_info of priv->apTD0Rings[i], with i increasing from 0. In case of > allocation failure, the memory is freed in reversed order, with i > decreasing to 0. However, the case i=0 is left out and thus memory is > leaked. > > Modify the memory freeing loop to include the case i=0. > > Signed-off-by: Nam Cao <namcaov@gmail.com> > --- > drivers/staging/vt6655/device_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/staging/vt6655/device_main.c b/drivers/staging/vt6655/device_main.c > index 3397c78b975a..a65014195fdc 100644 > --- a/drivers/staging/vt6655/device_main.c > +++ b/drivers/staging/vt6655/device_main.c > @@ -743,7 +743,7 @@ static int device_init_td0_ring(struct vnt_private *priv) > return 0; > > err_free_desc: > - while (--i) { > + while (i--) { > desc = &priv->apTD0Rings[i]; > kfree(desc->td_info); > } Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] staging: vt6655: fix potential memory leak 2022-09-09 14:13 [PATCH] staging: vt6655: fix potential memory leak Nam Cao 2022-09-09 14:42 ` Nam Cao 2022-09-09 17:59 ` Philipp Hortmann @ 2022-09-12 13:25 ` Dan Carpenter 2 siblings, 0 replies; 6+ messages in thread From: Dan Carpenter @ 2022-09-12 13:25 UTC (permalink / raw) To: Nam Cao, Ji-Hun Kim; +Cc: forest, gregkh, linux-kernel, linux-staging On Fri, Sep 09, 2022 at 04:13:39PM +0200, Nam Cao wrote: > In function device_init_td0_ring, memory is allocated for member > td_info of priv->apTD0Rings[i], with i increasing from 0. In case of > allocation failure, the memory is freed in reversed order, with i > decreasing to 0. However, the case i=0 is left out and thus memory is > leaked. > > Modify the memory freeing loop to include the case i=0. > > Signed-off-by: Nam Cao <namcaov@gmail.com> Looks good. Please add a Fixes tag, and CC all the people who were involved with the original patch so they can review it. Fixes: 5341ee0adb17 ("staging: vt6655: check for memory allocation failures") I actually wrote that buggy code and Ji-Hun copied it from me, so my bad. Sorry! regards, dan carpenter ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-09-12 16:14 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-09-09 14:13 [PATCH] staging: vt6655: fix potential memory leak Nam Cao 2022-09-09 14:42 ` Nam Cao 2022-09-12 14:17 ` Dan Carpenter 2022-09-12 14:53 ` Dan Carpenter 2022-09-09 17:59 ` Philipp Hortmann 2022-09-12 13:25 ` Dan Carpenter
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