3.16.57-rc1 review patch. If anyone has any objections, please let me know.
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From: Joe Lawrence joe.lawrence@redhat.com
commit fb910c42ccebf853c29296185c45c11164a56098 upstream.
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@redh... 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 [bwh: Backported to 3.16: - Drop changes in do_proc_douintvec_minmax_conv() - Adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2233,17 +2233,18 @@ static int do_proc_dopipe_max_size_conv( 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 (*negp || 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;