[v3 PATCH 3/3] mm/mempolicy: unify the parameter sanity check for mbind and set_mempolicy
From: Feng Tang <hidden>
Date: 2021-05-31 15:17:03
Also in:
lkml
Subsystem:
memory management, memory management - memory policy and migration, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
Currently the kernel_mbind() and kernel_set_mempolicy() do almost the same operation for parameter sanity check. Add a helper function to unify the code to reduce the redundancy, and make it easier for changing the pre-processing code in future. [thanks to David Rientjes for suggesting using helper function instead of macro] Signed-off-by: Feng Tang <redacted> --- mm/mempolicy.c | 47 +++++++++++++++++++++++++++++------------------ 1 file changed, 29 insertions(+), 18 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index c337bd7..85ef512 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c@@ -1444,26 +1444,37 @@ static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode, return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0; } +static inline int sanitize_mpol_flags(int *mode, unsigned short *flags) +{ + *flags = *mode & MPOL_MODE_FLAGS; + *mode &= ~MPOL_MODE_FLAGS; + if ((unsigned int)(*mode) >= MPOL_MAX) + return -EINVAL; + if ((*flags & MPOL_F_STATIC_NODES) && (*flags & MPOL_F_RELATIVE_NODES)) + return -EINVAL; + + return 0; +} + static long kernel_mbind(unsigned long start, unsigned long len, unsigned long mode, const unsigned long __user *nmask, unsigned long maxnode, unsigned int flags) { + unsigned short mode_flags; nodemask_t nodes; + int lmode = mode; int err; - unsigned short mode_flags; start = untagged_addr(start); - mode_flags = mode & MPOL_MODE_FLAGS; - mode &= ~MPOL_MODE_FLAGS; - if (mode >= MPOL_MAX) - return -EINVAL; - if ((mode_flags & MPOL_F_STATIC_NODES) && - (mode_flags & MPOL_F_RELATIVE_NODES)) - return -EINVAL; + err = sanitize_mpol_flags(&lmode, &mode_flags); + if (err) + return err; + err = get_nodes(&nodes, nmask, maxnode); if (err) return err; - return do_mbind(start, len, mode, mode_flags, &nodes, flags); + + return do_mbind(start, len, lmode, mode_flags, &nodes, flags); } SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
@@ -1477,20 +1488,20 @@ SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len, static long kernel_set_mempolicy(int mode, const unsigned long __user *nmask, unsigned long maxnode) { - int err; + unsigned short mode_flags; nodemask_t nodes; - unsigned short flags; + int lmode = mode; + int err; + + err = sanitize_mpol_flags(&lmode, &mode_flags); + if (err) + return err; - flags = mode & MPOL_MODE_FLAGS; - mode &= ~MPOL_MODE_FLAGS; - if ((unsigned int)mode >= MPOL_MAX) - return -EINVAL; - if ((flags & MPOL_F_STATIC_NODES) && (flags & MPOL_F_RELATIVE_NODES)) - return -EINVAL; err = get_nodes(&nodes, nmask, maxnode); if (err) return err; - return do_set_mempolicy(mode, flags, &nodes); + + return do_set_mempolicy(lmode, mode_flags, &nodes); } SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
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2.7.4