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authorJoe Lawrence <joe.lawrence@redhat.com>2017-11-17 15:29:28 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-17 16:10:03 -0800
commitfb910c42ccebf853c29296185c45c11164a56098 (patch)
treecea86df18f959e608924a42e5dfee88965e5a3cd /kernel
parent7a8d181949fb2c16be00f8cdb354794a30e46b39 (diff)
sysctl: check for UINT_MAX before unsigned int min/max
Mikulas noticed in the existing do_proc_douintvec_minmax_conv() and do_proc_dopipe_max_size_conv() introduced in this patchset, that they inconsistently handle overflow and min/max range inputs: For example: 0 ... param->min - 1 ---> ERANGE param->min ... param->max ---> the value is accepted param->max + 1 ... 0x100000000L + param->min - 1 ---> ERANGE 0x100000000L + param->min ... 0x100000000L + param->max ---> EINVAL 0x100000000L + param->max + 1, 0x200000000L + param->min - 1 ---> ERANGE 0x200000000L + param->min ... 0x200000000L + param->max ---> EINVAL 0x200000000L + param->max + 1, 0x300000000L + param->min - 1 ---> ERANGE In do_proc_do*() routines which store values into unsigned int variables (4 bytes wide for 64-bit builds), first validate that the input unsigned long value (8 bytes wide for 64-bit builds) will fit inside the smaller unsigned int variable. Then check that the unsigned int value falls inside the specified parameter min, max range. Otherwise the unsigned long -> unsigned int conversion drops leading bits from the input value, leading to the inconsistent pattern Mikulas documented above. Link: http://lkml.kernel.org/r/1507658689-11669-5-git-send-email-joe.lawrence@redhat.com Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Reported-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Mikulas Patocka <mpatocka@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Jens Axboe <axboe@kernel.dk> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sysctl.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 138b6484f277..dd25d90896fc 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2576,12 +2576,13 @@ static int do_proc_douintvec_minmax_conv(unsigned long *lvalp,
if (write) {
unsigned int val = *lvalp;
+ if (*lvalp > UINT_MAX)
+ return -EINVAL;
+
if ((param->min && *param->min > val) ||
(param->max && *param->max < val))
return -ERANGE;
- if (*lvalp > UINT_MAX)
- return -EINVAL;
*valp = val;
} else {
unsigned int val = *valp;
@@ -2632,17 +2633,18 @@ static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
struct do_proc_dopipe_max_size_conv_param *param = data;
if (write) {
- unsigned int val = round_pipe_size(*lvalp);
+ unsigned int val;
+ if (*lvalp > UINT_MAX)
+ return -EINVAL;
+
+ val = round_pipe_size(*lvalp);
if (val == 0)
return -EINVAL;
if (param->min && *param->min > val)
return -ERANGE;
- if (*lvalp > UINT_MAX)
- return -EINVAL;
-
*valp = val;
} else {
unsigned int val = *valp;

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